Question

1)Dada a função f(x) = -2x² + 8x, qual é o valor de: f(10), f(5), f(0), f(-1), f(-5)? 2)Qual é a raíz da função do 1º grau f(x) = -3x - 34?

Answer 1

$\textrm{Se } f(x) = -2x^2 + 8x\\\\\\\textrm{Entao: } \\\\f(10) = -2.10^2 + 8.10=-2.100 + 80=80-200=-120\\\\f(5) = -2.5^2 + 8.5=-2.25+40=40-50=-10\\\\f(0) = -2.0^2 + 8.0=0\\\\f(-1) = -2.(-1)^2 + 8.(-1)=-2-8=-10\\\\f(-5) = -2.(-5)^2 + 8.(-5)=-2.25-40=-50-40=-90$

$\textrm{Se } f(x) = -3x - 34\\\\\\\textrm{Entao a raiz ser\'a: }\\\\f(0)=-3.0-34=-34$