Question

dada a função f:r r definida por f(x)=ax + b, com a , b e R, calcular a e b, sabendo que f(2) = 8 e f(-2) = -4

Answer 1

Resposta:

$f(x)=ax+b ~~ com~f(2)=8~~=>\begin{cases}x=2\\ y=8\end{cases} \\ \\ 8=2a+b\\ \boxed{b=8-2a}-->(I)\\\\ com~f(-2)=-4~=>\begin{cases}x=-2\\ y=-4\end{cases}\\ \\ -4=-2a+b\\ \boxed{b=-4+2a}~-->(II)\\ \\ (I)=(II)\\ \\ 8-2a=-4+2a\\ 12=4a\\ \boxed{a=3}~~-->(*)$

$entao~substituindo\\(*)em~(I)\\b=8-2(3)\\\boxed{b=2}$