Giải:
a) \(x^2+5x=6\)
\(\Leftrightarrow x^2+5x-6=0\)
\(\Leftrightarrow x^2+6x-x-6=0\)
\(\Leftrightarrow\left(x^2+6x\right)-\left(x+6\right)=0\)
\(\Leftrightarrow x\left(x+6\right)-\left(x+6\right)=0\)
\(\Leftrightarrow\left(x+6\right)\left(x-1\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x+6=0\\x-1=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=-6\\x=1\end{matrix}\right.\)
Vậy ...
b) \(x^2-2015x+2014=0\)
\(\Leftrightarrow x^2-2014x-x+2014=0\)
\(\Leftrightarrow\left(x^2-2014x\right)-\left(x-2014\right)=0\)
\(\Leftrightarrow x\left(x-2014\right)-\left(x-2014\right)=0\)
\(\Leftrightarrow\left(x-2014\right)\left(x-1\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x-2014=0\\x-1=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=2014\\x=1\end{matrix}\right.\)
Vậy ...
Chúc bạn học tốt!
\(a,x^2+5x=6\)
\(\Rightarrow x^2+5x-6=0\)
\(\Rightarrow x^2+6x-x-6=0\)
\(\Rightarrow\left(x^2-6x\right)-\left(x+6\right)=0\)
\(\Rightarrow x\left(x+6\right)-\left(x+6\right)=0\)
\(\Rightarrow\left(x+6\right)\left(x-1\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x+6=0\\x-1=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=-6\\x=1\end{matrix}\right.\)
\(b,x^2+2015x+2014=0\)
\(\Rightarrow x^2+2015x+2015-1=0\)
\(\Rightarrow\left(x^2-1\right)+\left(2015x+2015\right)=0\)
\(\Rightarrow\left(x-1\right)\left(x+1\right)+2015\left(x+1\right)=0\)
\(\Rightarrow\left(x+1\right)\left(x-1+2015\right)=0\)
\(\Rightarrow\left(x+1\right)\left(x+2014\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x+1=0\\x+2014=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=-1\\x=-2014\end{matrix}\right.\)
a, x2+5x=6
\(\Rightarrow\) x2+5x-6 =0
\(\Leftrightarrow\) x2 -x+6x-6=0
\(\Leftrightarrow\)x ( x-1)+6(x-1) =0
\(\Leftrightarrow\) (x-1)(x-6)=0
\(\Rightarrow\) x-1=0 hoặc x-6=0
\(\Leftrightarrow\) x=1 hoặc x=6
Vậy..........
b, x2-2015x+2014 =0
\(\Leftrightarrow\) x2- 2014x-x+2014=0
\(\Leftrightarrow\)x(x-2014)-(x-2014)=0
\(\Leftrightarrow\)(x-1)(x-2014)=0
\(\Rightarrow\) x-1=0 hoặc x-2014=0
\(\Leftrightarrow\) x=1 hoặc x=2014
Vậy...........
