Diketahui g(x) = 5x + 3 dan fog(x) = 10x + 7. Maka f(x) = ...?

[tex](fog)(x) = 10x + 7 \\ f(g(x)) = 10x + 7 \\ f(5x + 3) = 10x + 7 \\ f(5x + 3) = 2(5x + 3) + 1 \\ andai \: 5x + 3 = k \: maka \\ f(k) = 2k + 1 \\ f(x) = 2x + 1[/tex]