Question

a)( 4x - 3 ) . ( 2x + 5 ) =​

Answer 1

Resposta:

Explicação passo a passo:

Aplicando distributiva:

8$x^{2}$ + 20x - 6x -15 = 0

8$x^{2}$ +14x -15 = 0

Fazer bhaskara:

x = -b ± $\frac{\sqrt{b^{2} - 4.a.c}}{2.a}$

$x_{1}$ = -14 +$\frac{\sqrt{14^{2}- 4.8.(-15)} }{2.8}$= -14 + $\frac{ \sqrt{196 + 480}}{16}$ = -14 + $\frac{\sqrt{676} }{16}$  =-14+ $\frac{26}{16}$ = -14 +$\frac{13}{8}$

$x_{1}$ = $\frac{(-14.8)+13}{8}$ =$\frac{(-112)+13}{8}$ =$\frac{99}{8}$

$x_{2}$ = -14 -$\frac{\sqrt{14^{2}- 4.8.(-15)} }{2.8}$= -14 - $\frac{ \sqrt{196 + 480}}{16}$ = -14 - $\frac{\sqrt{676} }{16}$  =-14- $\frac{26}{16}$ = -14 -$\frac{13}{8}$

$x_{2}$ = $\frac{(-14.8)-13}{8}$ =$\frac{(-112)-13}{8}$ =$\frac{-125}{8}$