đáp

án là

A

.

.

đk : \(x\ge-1\)

Đặt \(\sqrt{x+1}=b\Rightarrow\hept{\begin{cases}x^3+b=1\\b^2=x+1\end{cases}}\) rút \(b=1-x^3\text{ thế xuống phương trình dưới ta có : }\)

\(\left(1-x^3\right)^2=x+1\Leftrightarrow1-2x^3+x^6=x+1\Leftrightarrow x\left(x^5-2x^2-1\right)=0\)

Vậy \(\orbr{\begin{cases}x=0\\x^5-2x^2-1=0\end{cases}}\) mà chú ý \(b=1-x^3\ge0\Rightarrow x\le1\Rightarrow x^5< 2x^2+1\)

nên phương trình \(x^5-2x^2-1=0\text{ không có nghiệm nào thỏa mãn}\)

vậy pt có nghiệm duy nhất x=0

kq

bằng 

=16523465

nhá ,;

,

\(\sqrt{46x=t85756+5682\left(5788\right)6778}\)

ĐK : x\(\ge\)- 1

\(x^2+\sqrt{x+1}=1\)

<=> \(\sqrt{x+1}=1-x^2\)

<=> \(x+1=1-2x^2+x^4\)

<=> \(x^4-2x^2-x=0\)

<=> \(x\left(x^3-2x-1\right)=0\)

<=> \(x\left(x+1\right)\left(x^2-x-1\right)=0\)

<=> \(\hept{\begin{cases}x=0\\x=-1\\\left(x-\frac{1}{2}\right)^2=\frac{5}{4}\end{cases}}\)<=> x = 0 ; x = - 1 ; x = \(\frac{1+\sqrt{5}}{2};\frac{1-\sqrt{5}}{2}\)

Vậy...

x=0 à

phải ko

\(x^2+\sqrt{x+1}=1\)ĐK : x >= -1 

\(\Leftrightarrow x^2-1+\sqrt{x+1}=0\Leftrightarrow\left(x-1\right)\left(x+1\right)+\sqrt{x+1}=0\)

\(\Leftrightarrow\sqrt{x+1}\left[\sqrt{x+1}\left(x-1\right)+1\right]=0\)

TH1 : \(\sqrt{x+1}=0\Leftrightarrow x=-1\)

TH2 : \(\sqrt{x+1}=-\frac{1}{x-1}\Leftrightarrow x+1=\frac{1}{\left(x-1\right)^2}\)

\(\Leftrightarrow\left(x+1\right)\left(x^2-2x+1\right)=1\Leftrightarrow x^3-2x^2+x+x^2-2x+1=1\)

\(\Leftrightarrow x^3-x^2-x=0\Leftrightarrow x\left(x^2-x-1\right)=0\)

\(\Leftrightarrow x=0;x=\frac{1\pm\sqrt{5}}{2}\)

ĐKXĐ: x≥−2x≥−2

2(x2−x+6)=5√x3+82(x2−x+6)=5x3+8

⇔2(x2−x+6)=5√(x+2)(x2−2x+4)⇔2(x2−x+6)=5(x+2)(x2−2x+4)

Đặt {√x+2=a≥0√x2−2x+4=b>0{x+2=a≥0x2−2x+4=b>0

⇒2(a2+b2)=5ab⇒2(a2+b2)=5ab

⇔2a2−5ab+2b2=0⇔2a2−5ab+2b2=0

⇔(a−2b)(2a−b)=0⇔(a−2b)(2a−b)=0

⇒[a=2b2a=b⇒[a=2b2a=b ⇒[√x+2=2√x2−2x+42√x+2=√x2−2x+4⇒[x+2=2x2−2x+42x+2=x2−2x+4

⇒[x+2=4(x2−2x+4)4(x+2)=x2−2x+4⇒[x+2=4(x2−2x+4)4(x+2)=x2−2x+4

⇒...

Đừng cho mình nhé ko phải do mình làm chỉ nhờ trang mạng khác để giúp cậu thôi nhé

TH2 có hơi sai sai nhé..

( Đ hiểu kiểu gì mà mấy bạn cứ trả lời TH2, thôi thì mình sửa lại vậy =)) )

TH2 : a = 2 - b => a² = b² - 4b + 4. Thay vào (**) ta có :

a² - b² = 2x <=> - 4b + 4 = 2x

<=> - 2b = x - 2

<=> 4b² = x² - 4x + 4

<=> 4 - 4x = x² - 4x + 4

<=> x² - 4x + 4 + 4x - 4 = 0

<=> x² = 0 <=> x = 0 (tmđk)

Vậy pt có tập nghiệm S = { - 3/5 ; 0 }

kick????

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CHÚC BẠN HT 

Forests play an important part of life on earth. They absorb Co2 and harmful gases produced during burning fossil fuels, which reduce air pollution, heat, flood and other disasters. They are also home of a wide variety of fauna and floral.

Nontheless, nowadays, jungles’ area is decreasing because of exploitation of woods and land. So what we can do to stop them from disappearing gradually? First, build plans carefully of land use for public facilities and cultivation. Furthermore, the land that trees were cut down needs to be replaced by new plants and be taken care properly. Last but not least, government must raise awareness on the importance of trees in education, and build tree-growing campaigns across the country.

To sum up, forests must be protected to maintain the life on earth and steps must be taken to prevent further consequences.