(x-1).(1-x)=-64 tìm x

Đáp án:

($x-1$).($1-x$)$=-64$

$⇒x-x^{2}-1+x+64=0$

$⇒-x^{2}-2x+63=0$

$⇒x^{2}-2x-63=0$

$⇒x^{2}+7x-9x-63=0$

$⇒x$($x+7$)$-9$($x+7$)$=0$

$⇒$($x+7$).($x+9$)$=0$

$⇒$\(\left[ \begin{array}{l}x+7=0\\x-9=0\end{array} \right.\) 

$⇒$\(\left[ \begin{array}{l}x=-7\\x=9\end{array} \right.\)