Question

Calcule os valores de X para as seguintes funções quadráticas:

F(X)= (x + 2). (–x + 5)

Answer 1

Resposta:

S = {-2, 5}

Explicação passo a passo:

$\left(x+2\right)\left(-x+5\right)$

$=x\left(-x\right)+x\cdot \:5+2\left(-x\right)+2\cdot \:5$

$=-xx+5x-2x+2\cdot \:5$

$=-x^2+3x+10$

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

$x_{1,\:2}=\frac{-3\pm \sqrt{3^2-4\left(-1\right)\cdot \:10}}{2\left(-1\right)}$

$x_{1,\:2}=\frac{-3\pm \:7}{2\left(-1\right)}$

$x_1=\frac{-3+7}{2\left(-1\right)},\:x_2=\frac{-3-7}{2\left(-1\right)}$

$x_1=\frac{-3+7}{2\left(-1\right)}=\frac{-3+7}{-2\cdot \:1}=\frac{4}{-2\cdot \:1}=\frac{4}{-2}=-\frac{4}{2}=-2$

$x_2=\frac{-3-7}{2\left(-1\right)}=\frac{-3-7}{-2\cdot \:1}=\frac{-10}{-2\cdot \:1}=\frac{-10}{-2}=\frac{10}{2}=5$

$x=-2,\:x=5$