Help bài 2,4,5 nhé 
K
Khách
Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
Những câu hỏi liên quan
NN
2
29 tháng 5 2022
Câu 1
0.25*1/100+0,75*0,01
=0,25*0,01+0,75*0,01
=0,0025+0,0075
=0,01
Câu 2
47/5;[47/5*4/7]
=47/5;188/35
=329/188
[2/15*8/17*27/12];4/17
=72/85;4/17
=18/5
Xin thông cảm nha, máy của mình bị hết pin nên không làm đến bài 3 được. Khi nào máy mình đầy pin thì mình sẽ làm hết bài 3 của bạn nha.
DN
3
29 tháng 5 2022
Câu 4: Tính bằng cách thuận tiện nhất:
\(3,8\times4,54+3,6:1,5+5,46\times3,8-2,1:1,5\)
\(=3,8\times\left(5,54+5,46\right)+\left(3,6-2,1\right):1,5\)
\(=3,8\times10+1,5:1,5\)
\(=\left(3,8\times10\right)+\left(1,5:1,5\right)\)
\(=38+1=39\)
Câu 5: Tính nhanh:
\(\left(1-\dfrac{1}{2}\right)\times\left(1-\dfrac{1}{3}\right)\times\left(1-\dfrac{1}{4}\right)\times\left(1-\dfrac{1}{5}\right)\)
\(=\dfrac{1}{2}\times\dfrac{2}{3}\times\dfrac{3}{4}\times\dfrac{4}{5}\)
\(=\dfrac{1\times2\times3\times4}{2\times3\times4\times5}\)
\(=\dfrac{1}{5}\)
3 tháng 10 2021
Áp dụng tính chất của dãy tỉ số bằng nhau, ta được:
\(\dfrac{x}{\dfrac{1}{2}}=\dfrac{y}{\dfrac{1}{4}}=\dfrac{z}{\dfrac{1}{5}}=\dfrac{x+y+z}{\dfrac{1}{2}+\dfrac{1}{4}+\dfrac{1}{5}}=\dfrac{38}{\dfrac{19}{20}}=40\)
Do đó: x=20; y=10; z=8
16 tháng 8 2017
2 dễ rồi, suy nghĩ đy nhé
4) \(15-\left\{2\left[x-\left(2x-4\right)\cdot5\right]-3\left(x+1\right)\right\}=12-x\)
\(\Rightarrow15-\left[2\left(x-10+20\right)-3x-3\right]=12-x\)
\(\Rightarrow15-\left(2x-20+40-3x-3\right)=12-x\)
\(\Rightarrow15+x-17=12-x\)
\(\Rightarrow x+x=12-15+17\)
\(\Rightarrow2x=14\Rightarrow x=\dfrac{14}{2}=7\)
5) \(\left(\dfrac{3}{1\cdot2}+\dfrac{3}{2\cdot3}+\dfrac{3}{3\cdot4}+...+\dfrac{3}{89\cdot90}\right)-2x=\dfrac{2}{1\cdot3}+\dfrac{2}{3\cdot5}+\dfrac{2}{5\cdot7}+...+\dfrac{2}{97\cdot99}\)
\(\Rightarrow3\left(\dfrac{1}{1\cdot2}+\dfrac{1}{2\cdot3}+\dfrac{1}{3\cdot4}+\cdot\cdot\cdot+\dfrac{1}{89\cdot90}\right)-2x=1-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{5}+\cdot\cdot\cdot+\dfrac{1}{97}-\dfrac{1}{99}\)
\(\Rightarrow3\left(1-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+...+\dfrac{1}{89}-\dfrac{1}{90}\right)-2x=1-\dfrac{1}{99}\)
\(\Rightarrow3\left(1-\dfrac{1}{90}\right)-2x=\dfrac{98}{99}\)
\(\Rightarrow-2x=\dfrac{98}{99}-3\left(1-\dfrac{1}{90}\right)=\dfrac{98}{99}-\dfrac{89}{30}=-\dfrac{1957}{990}\)
\(\Rightarrow x=-\dfrac{1957}{990}:\left(-2\right)=\dfrac{1957}{1980}\)
Vậy.............
BN
2
8 tháng 12 2021
Bài 3:
Gọi số cây là x
Theo đề, ta có: \(x\in BC\left(3;8;10\right)\)
hay x=600
22 tháng 4 2016
Mình làm topic 2 nha:
My most favorite season is fall and I love everything about it. Usually it starts at the end of May in our country and lasts till the middle of July.
The weather is best during fall and you won't feel the heat of summer or the cold wind of winter. The nature arranges itself with the beautiful green and flowers are noticed all around the places.
I like the scenic beauty, charming weather, festivities and freshness of this season. This is a distinctive season and is known as the queen of seasons in our country. The newly grown green leaves of trees, the colorful flowers, the chirping of the birds and crisp and mild air of fall are some of the noticeable changes in our country. After the hot summer ends, the falls comes and people in our country love this season.
Fall is season that marks the transition from summer into winter and the night falls later than winter. The farmers start harvesting seeds in this season and they become quite active during this season.
I usually get vacation at the beginning of the fall and visit my hometown. This is a perfect vacation for me as my hometown becomes even more beautiful. Because of geographical location and culture, we have 2-3 major festival during this time and people enjoys the festivals and weathers.
D
23 tháng 4 2016
As a student, I don’t have much free time beside those I love, so my summer vacation is the duration during which I often busy myself with many things at home all day. In the day time,
I often do sundry things for my grandmother and help my parents to do housework. In the evening, I go out with some of my old friends.
We often chat with each other in a cafe. Usually, when I am free from doing housework, I go and visit close relatives in my neighborhood and ask them about their life and business. In the late evening, I watch films on TV or read novels or books to widen my understanding. I often
go to bed very late.
In my mind, I always want my short summer vacations to be not only comfortable for me but also useful for my beloved people.
Chúc bạn học tốt
HN
3
15 tháng 1 2022
Tổng số tuổi của bố,mẹ và Cúc là:
30x3=90(tuổi)
Tổng số tuổi của mẹ và Cúc là:
24x2=48(tuổi)
Số tuổi của bố Cúc là:
90-48=42(tuổi)
Bài 2:
a: ĐKXĐ: x<>1; x<>-1
b: \(=\dfrac{x}{2\left(x-1\right)}-\dfrac{3}{2\left(x+1\right)}-\dfrac{1}{\left(x-1\right)\left(x+1\right)}\)
\(=\dfrac{x^2+x-3x+3-2}{2\left(x-1\right)\left(x+1\right)}=\dfrac{x^2-2x+1}{2\left(x-1\right)\left(x+1\right)}=\dfrac{x-1}{2\left(x+1\right)}=\dfrac{x-1}{2x+2}\)
c: Để P=2 thì 4x+4=x-1
=>3x=-5
=>x=-5/3
Thank you so much