Question

calcule? (-x+5) (x +2)

Answer 1

$(-x+5)(x+2)$

$-x^{2} -2x+5x+10$

$- x^{2} +3x+10$

Equação do 2º Grau

$-x^{2} +3x+10=0$

Δ=$3^{2}-4*(-1)*10$
Δ=$3^{2} +40$
Δ=$9+40$
Δ=$49$

$x_{1,2}$ = $\frac{(-3 ± \sqrt{19} )}{-2}$

$x_{1,2}$ = $\frac{(-3)±7}{-2}$

$x_{1}$ = $\frac{(-3)+7}{-2}$

$x_{1}$= $\frac{4}{-2}$

$x_{1}$ = $-2$

$x_{2}$ = $\frac{-3-7}{-2}$

$x_{2}$ = $\frac{-10}{-2}$

$x_{2}$ = $5$