Tớ nghĩ là lực kéo , vì mình phải kéo cỏ ra khỏi mặt đất.

Tớ nghĩ là không cần nhổ cỏ đâu , cứ lấy máy cắt cỏ ra mà dùng ấy . :))

a) \(\frac{x^2+2x+4}{4x^3-32}=\frac{x^2+2x+4}{4\left(x^3-8\right)}=\frac{x^2+2x+4}{4\left(x-2\right)\left(x^2+2x+4\right)}=\frac{1}{4\left(x-2\right)}.\)

 b) \(\frac{10x-15}{4x^2-9}=\frac{5\left(2x-3\right)}{\left(2x\right)^2-3^2}=\frac{5\left(2x-3\right)}{\left(2x-3\right)\left(2x+3\right)}=\frac{5}{2x+3}.\)

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^HAND!!!!

\(\frac{x^2+2x+4}{4x^3-32}=\frac{\left(x+2\right)^2}{4\left(x^3-8\right)}=\frac{\left(x+2\right)^2}{4\left(x-2\right)\left(x^2+2x+4\right)}=\frac{x+2}{4\left(x^2+2x+4\right)}.\)

\(\frac{10x-15}{4x^2-9}=\frac{5\left(2x-3\right)}{\left(2x\right)^2-3^2}=\frac{5\left(2x-3\right)}{\left(2x-3\right)\left(2x+3\right)}=\frac{5}{2x+3}\)

Ta có :

\(\frac{y^3-y}{5y+y}=\frac{y\left(y^2-1\right)}{6y}=\frac{y^2-1}{6}.\)

Đúng nhé!

_HAND!!!!

giúp mk vs ai đúng nk k cho

Để \(x^3+8x^2+5x+a\)chia hết cho \(x^2+3x+b\)

\(\Leftrightarrow\left(5-b-15\right)x+a-5b=0\)

\(\Leftrightarrow\left(b-10\right)x+\left(a-5b\right)=0\)

\(\Leftrightarrow\hept{\begin{cases}b-10=0\\a-5b=0\end{cases}\Leftrightarrow}\hept{\begin{cases}b=10\\50\end{cases}}\)

Vậy ...

a) \(\frac{x^2-49}{2x+1}.\frac{3}{7-x}=\frac{\left(x-7\right)\left(x+7\right)}{2x+1}.\frac{-3}{x-7}=\frac{-3\left(x-7\right)\left(x+7\right)}{\left(2x+1\right)\left(x-7\right)}=\frac{-3\left(x+7\right)}{2x+1}\)

\(=\frac{-3x-21}{2x+1}\)

b) \(\frac{3x^2-2x}{x^2-1}.\frac{1-x^4}{\left(2-3x\right)^3}=\frac{x\left(3x-2\right)}{x^2-1}.\frac{x^4-1}{\left(3x-2\right)^3}=\frac{x\left(3x-2\right)}{x^2-1}.\frac{\left(x^2-1\right)\left(x^2+1\right)}{\left(3x-2\right)^3}\)

\(=\frac{x\left(3x-2\right)\left(x^2-1\right)\left(x^2+1\right)}{\left(x^2-1\right)\left(3x-2\right)^3}=\frac{x\left(x^2+1\right)}{\left(3x-2\right)^2}=\frac{x^3+x}{\left(3x-2\right)^2}\)

\(\frac{x^2-49}{2x+1}.\frac{3}{7-x}=\frac{\left(x-7\right)\left(x+7\right)}{2x+1}.\left(-\frac{3}{x-7}\right)=\frac{-3\left(x+7\right)}{2x+1}=\frac{-3x-21}{2x+1}\)

\(5x^2+8xy+5y^2+4x-4y+8=0\)

\(\Leftrightarrow\left(x^2+4x+4\right)+\left(y^2-4y+4\right)+4x^2+4y^2+8xy=0\)

\(\Leftrightarrow\left(x+2\right)^2+\left(y-2\right)^2+4\left(x+y\right)^2=0\)

\(\Leftrightarrow x=-2;y=2\)

Thay vào P ta có:

\(P=\left(2-2\right)^8+\left(1-2\right)^{11}+\left(2-1\right)^{2018}\)

\(=0-1+1=0\)