Question

Solve:
$3x^2+7x-20=0$

Answer 1

$\begin{array}{c}3x^2+7x-20=0\\ \Rightarrow 3x^2+12x-5x-20=0\\ \Rightarrow 3x\left(x+4\right)-5\left(x+4\right)=0\\ \Rightarrow \left(3x-5\right)=0\\ \Rightarrow 3x=5\\ \Rightarrow x=\frac{5}{3}\\ \Rightarrow x+4=0\\ \Rightarrow x=-4\\ x=\frac{5}{3},-4\end{array}$