Question

Dada a função f(x)  x/3 - 1, determine A= f (-1) + f(3) - 2f(0).

Answer 1

$f\left(x \right )=\dfrac{x}{3}-1\\ \\ \\ \bullet\;\; f\left(-1 \right )=\dfrac{-1}{3}-1\\ \\ f\left(-1 \right )=\dfrac{-1-3}{3}\\ \\ f\left(-1 \right )=-\dfrac{4}{3}\\ \\ \\ \bullet\;\; f\left(3 \right )=\dfrac{3}{3}-1\\ \\ f\left(3 \right )=1-1\\ \\ f\left(3 \right )=0\\ \\ \\ \bullet\;\; f\left(0 \right )=\dfrac{0}{3}-1\\ \\ f\left(0 \right )=0-1\\ \\ f\left(0 \right )=-1$


Então,

$A=f\left(-1 \right )+f\left(3 \right )-2f\left(0 \right )\\ \\ A=-\dfrac{4}{3}+0-2\cdot \left(-1 \right )\\ \\ A=-\dfrac{4}{3}+0+2\\ \\ A=-\dfrac{4}{3}+2\\ \\ A=\dfrac{-4+6}{3}\\ \\ A=\dfrac{2}{3}$