Resposta :
f9X)=2x+1 ==>f(g(x) = 2g(x) + 1
f(g(x))=2x²-9
2g(x) + 1 = 2x²-9
2.g(x) = 2x²-9 - 1
2.g(x) = 2x² - 10
g(x) = 2(x² - 5)
2
g(x) = x^2 - 5
g(-2) = (-2)^2 - 5
g(-2) = 4 - 5
g(-2) = - 1
f(g(x))=2x²-9
2g(x) + 1 = 2x²-9
2.g(x) = 2x²-9 - 1
2.g(x) = 2x² - 10
g(x) = 2(x² - 5)
2
g(x) = x^2 - 5
g(-2) = (-2)^2 - 5
g(-2) = 4 - 5
g(-2) = - 1