Question

Calcule o valor das equações abaixo
A ) x^2-x-20=0
B)x^2-3x-4=0

Answer 1

A)

$x^{2} -x-20=0\\D=b^{2} -4ac\\D=+1+80\\D=81\\\\x=\frac{-b\±\sqrt{D} }{2.a\\}\\x=\frac{+1+9}{2} \\x'= \frac{10}{2} = 5\\x''=\frac{-8}{2} = -4$

B)

$x^{2} -3x-4=0\\D= b^{2}-4ac\\D=+9+16\\D=25\\\\x=\frac{-b\±\sqrt{D} }{2.a}\\x'=\frac{3+5}{2} =4\\x''=\frac{3-5}{2}=-1$