Đáp án:
$\text{a) 2x-15 = -47}$
$\text{<=> 2x = -47 + 15}$
$\text{<=>2x = -32}$
$\text{<=> x = -32 : 2}$
$\text{<=> x = -16}$
$\text{Vậy x = {-16} }$
$\text{b) (-5)² - (5x-3) = 43}$
$\text{<=> 25 - 5x + 3 =43}$
$\text{<=> -5x = 43 -3 - 25}$
$\text{<=> -5x = 15}$
$\text{<=> x = 15 : (-5)}$
$\text{<=> x = -3}$
$\text{Vây x = {-3}}$
$\text{c) (x-3)(2x+6) =0}$
$\text{<=>\(\left[ \begin{array}{l}x-3=0\\2x+6=0\end{array} \right.\) }$
$\text{<=> \(\left[ \begin{array}{l}x=3\\x=-3\end{array} \right.\) }$
$\text{Vậy x = { 3 ;-3} }$
