Question

qual é a soma das raizes da funçao f(x)=x2+8x+9?

Answer 1

Resposta:

-8

Explicação passo a passo:

$f(x)=x^2+8x+9\\x^2 +8x+9=0\\a=1, b=8 c=9\\\\ \frac{-b +_-\sqrt{b^2 -4.a.c} }{2.a}\\\\\frac{-8+_-\sqrt{8^2-4.1.9} }{2.1}\\\frac{-8+_-\sqrt{64-36} }{2}\\\frac{-8+_-2\sqrt{7} }{2}\\x'=\frac{-8+2\sqrt{7} }{2}=-4+\sqrt{7} }\\x''=\frac{-8-2\sqrt{7} }{2}=-4-\sqrt{7}\\ (-4+\sqrt{7} })+(-4-\sqrt{7})\\-4-4+\sqrt{7}-\sqrt{7}\\-4-4=-8$