ừ thì mình sẽ giúp bạn mà câu a bạn viết sai đề nha
1/a)\(2x^2+3x-5=2x^2-2x+5x-5=2x\left(x-1\right)+5\left(x-1\right)=\left(2x+5\right)\left(x-1\right)\)
b)\(4x^2-3x-1=4x^2-4x+x-1=4x\left(x-1\right)+\left(x-1\right)=\left(4x+1\right)\left(x-1\right)\)
c)Sai đề: \(3x^2+6xy+3y^2-3z^2\)
\(=3\left(x^2+2xy+y^2-z^2\right)\)
\(=3\left[\left(x+y\right)^2-z^2\right]\)
\(=3\left(x+y+z\right)\left(x+y-z\right)\)
d)Sai đề:\(x^3-2x^2y+xy^2-9x=x\left(x-2xy+y^2-9\right)=x\left[\left(x-y\right)^2-9\right]=x\left(x-y+3\right)\left(x-y-3\right)\)
e)\(2x-2y-x^2+2xy-y^2=2\left(x-y\right)-\left(x-y\right)^2=\left(x-y\right)\left(2-x+y\right)\)
f)Hình như sai đề đúng không?
\(x^3-x+3x^2y+3xy^2+y^3-y\)
\(=\left(x+y\right)^3-\left(x+y\right)\)
\(=\left(x+y\right)\left[\left(x+y\right)^2-1\right]\)
\(=\left(x+y\right)\left(x+y+1\right)\left(x+y-1\right)\)
2/a.\(7x-6x^2-2=0\)
\(\Leftrightarrow-\left(6x^2-3x-4x+2\right)=0\)
\(\Leftrightarrow3x\left(x-1\right)-2\left(x-1\right)=0\)
\(\Leftrightarrow\left(3x-2\right)\left(x-1\right)=0\)
\(\Rightarrow\left\{{}\begin{matrix}3x-2=0\\x-1=0\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}x=\dfrac{2}{3}\\x=1\end{matrix}\right.\)
b.\(16x-5x^2-3=0\)
\(\Leftrightarrow-\left(5x^2-15x-x+3\right)=0\)
\(\Leftrightarrow5x\left(x-3\right)-\left(x-3\right)=0\)
\(\Leftrightarrow\left(5x-1\right)\left(x-3\right)=0\)
\(\Rightarrow\left\{{}\begin{matrix}5x-1=0\\x-3=0\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}x=\dfrac{1}{5}\\x=3\end{matrix}\right.\)
c.\(2x^2+3x-5=0\)
\(\Leftrightarrow2x^2-2x+5x-5=0\)
\(\Leftrightarrow2x\left(x-1\right)+5\left(x-1\right)=0\)
\(\Leftrightarrow\left(2x+5\right)\left(x-1\right)=0\)
\(\Rightarrow\left\{{}\begin{matrix}2x+5=0\\x-1=0\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}x=-\dfrac{5}{2}=-2,5\\x=1\end{matrix}\right.\)
