cảm ơn trước ^^

Ko chép mạng nhé

ta có : 1.2+2.3+3.4+.....+99.100=99.100.101 /3 =333300

mà 1.2+2.3+....+9.10+9.10.11/3=330

=>E= 333300-330=332970

\(\frac{x}{z}=\frac{z}{y}\Rightarrow z^2=xy\)

\(\Rightarrow\frac{x^2+z^2}{y^2+z^2}=\frac{x^2+xy}{y^2+xy}=\frac{x\left(x+y\right)}{y\left(x+y\right)}=\frac{x}{y}\)

\(x.x+y.y+z.z=12\)

\(\Leftrightarrow\frac{x^2}{1}+\frac{y^2}{1}+\frac{z^2}{1}=\frac{12}{3}=4\)

\(\Rightarrow x^2=1.4=4\Leftrightarrow x=2\)

\(y^2=1.4=4\Leftrightarrow y=2\)

\(z^2=1.4=4\Leftrightarrow z=2\)

Áp dụng BĐT Cauchy - schwarz:

\(x^2+y^2+z^2=\frac{x^2}{1}+\frac{y^2}{1}+\frac{z^2}{1}\ge\frac{\left(x+y+z\right)^2}{1+1+1}=\frac{36}{3}=12\)

(Dấu "="\(\Leftrightarrow x=y=z\))

\(pt\Leftrightarrow3x^2=12\Leftrightarrow x^2=4\Leftrightarrow x=\pm2\)

\(\Rightarrow\orbr{\begin{cases}x=y=z=2\\x=y=z=-2\left(L\right)\end{cases}}\)(Vì x + y + z = 6)

Vậy x = y = z = 2

ok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok okok ok ok

Tham khảo :

https://nld.com.vn/cong-doan/nghi-ve-bua-com-gia-dinh-20170627215434778.htm

Nghĩ về bữa cơm gia đình

Hok tốt ~~

thơm ngo bổ  rẻ

Quê tôi là một vùng trung du, đồi núi nối đuôi nhau chạy mãi tới tít chân trời xa. Thỉnh thoảng có một vài thung lũng nhỏ hẹp chạy dài dưới hai chân đồi, tạo thành một cánh đồng dài, hẹp. Đó là vùng Thạch Thành quê ngoại tôi.

Cánh đồng nhỏ hẹp ấy như một dải lụa xanh chạy dài từ xã Thành Minh đến tận đường Quốc lộ 1A. “Dải lụa” ấy dã nuôi sống gần như nửa cái huyện Thạch Thành vùng trung du này. Dân đông, ruộng ít, ấy vậy mà cuộc sống ở dây không đến nỗi lam lũ, nghèo đói. Dường như quanh năm vụ nối vụ, mùa nối mùa. Hết màu xanh mơn mởn của cây lúa thời con gái thì đến màu vàng óng ả của mùa gặt, hết lúa lại khoai đến ngô, sắn, rau màu cứ thế luôn nhuộm mới màu sắc cho dải đất này những sắc hương của cuộc sống thanh bình đang từng ngày thay da đổi thịt.

Trước mắt, giờ lúa đang che kín cả mặt ruộng. Gió xuân từ trên các đồi cao thổi về thung lũng tạo nên những đợt sống lúa đuôi nhau vội vàng, phát ra những âm thanh dịu ngọt. Đây đó, những người đi ra thăm ruộng lúc ẩn, lúc hiện làm cho những chú chim đang bắt sâu cho lúa giật mình vọt lên cao rồi sải cánh bay về một bụi cây nào đó trên đồi cao. Ở dọc chân đồi, người ta xẻ ruộng thành những bậc thang để trồng bắp cải, su hào.. Những luống bắp cải tươi tốt đã bắt đầu cuộn lại. Có những bắp mới cuốn được một nửa mà đã to bằng phần trên của chiếc mũ cối, chắc khi cuộn hết nó phải nặng đến bốn, năm kí. Xuyên qua giữa cánh đồng là tỉnh lộ nối từ Quốc lộ 1A đến thị trấn Kim Tân, trung tâm của huyện Thạch Thành. Những chiếc xe bò đang chở phân ra đồng bón cho lúa, lăn đều trên mặt đường nhựa cùng với tiếng gõ lộc cộc của những bước chân đều đặn nện xuống mặt đường tạo ra một âm thanh vui nhộn giữa cánh đồng. Nắng đã lên cao, vậy mà tôi vẫn tần ngần ngắm mãi “dải lụa” xanh này không biết chán. Mai đây khi mùa gặt đến, cánh đồng lại rộn rã tiếng hát, cười của những người nông dân “một nắng hai sương” đi thu hoạch lúa.

Màu xanh hôm nay, màu xanh của niềm tin, của hi vọng chắc chắn sẽ báo hiệu một mùa gặt bội thu.

Sáng sớm tinh mơ, em cùng mẹ đi thăm đồng, đường làng chưa có một dấu chân qua. Cánh đồng lúa chín như tấm thảm nhung óng ánh, chúng đã níu chân em dừng lại. Em đã nhận ra vẻ đẹp của đồng lúa đang sắp sửa vào mùa.

Cánh đồng hiện lên với tất cả nét đẹp giản dị của nó trong ánh mặt trời. Hàng ngàn bông lúa vàng tươi, chắc nịch, cong oằn, ngả đầu vào nhau như muốn nói một điều: Ngày mùa đến rồi đấy! Từ trong biển lá đã ngả sang màu úa ngát dậy một mùi hương ngây ngất. Mùi hương của cỏ hoa, đồng nội, mùi hương lúa mới. Trên đầu ngọn lúa, sương treo lóng lánh như kim cương. Một vài giọt sương tung tăng nhảy nhót trên kẽ lá rồi tan dần theo hơi ấm mặt trời.

Làn gió nhẹ thoảng qua, những bông lúa nhẹ nhàng mấp máy. Sóng lúa nhấp nhô như gợn sóng vỗ bờ. Mặt trời lên cao dần, ánh nắng óng ả lọt xuống lòng đất. Từng đàn bướm là là chao lượn trên ngọn lúa. Tất cả đượm một màu vàng trù phú, đầm ấm lạ lùng. Xa xa, thấp thoáng bóng người đi tháo nước, be bờ. Hơi thở của đất trời, hơi nước thơm thơm, man mác thật đặc trưng của đồng quê.

Cánh đồng lúa ửng lên một màu vàng xuộm, nắng ngả màu vàng hoe. Từng dòng người đổ ra đồng gặt hái, nón trắng nhấp nhô trên các thửa ruộng ven bờ. Tiếng nói chuyện rầm rì, tiếng gọi nhau í ới. Ai cũng rạng rỡ nụ cười trước cảnh vụ mùa no ấm. Đâu đó, tiếng hót lảnh lót của con chim chiền chiện. Chúng lượn vòng trên cánh đồng rồi bay lên trên vòm trời xanh trong và cao vút.

Em yêu cánh đồng này lắm. Nơi ấy có bao bàn tay lao động của con người, họ không ngần ngại nắng mưa, vất vả. Họ luôn cấy trồng, luôn gieo hạt giống cho mùa sau.

Hok tốt