Diketahui f(x)=4x+5 dan g(x)=a(x+5).jika (fog)(x)=x,nilai a adalah

jawab

f(x) = 4x - 5

g(x) = a(x + 5)

fog(x)  = x

f{g(x)} = x

f{ax + 5a) = x

4(ax + 5a) - 5 = x

4ax + 20a  = x + 5

a(4x + 20) = x + 5

a = (x + 5)/(4x + 20)

a = (x + 5) / 4(x + 5)

a = 1/4 → jawaban