tolong jawabannya + penjelasannya ya... Jika f(xy)=f(x+y) dan f(7)=7. Tentukanlah nilai f(49)

f(49)=f(7x7)=f(7+7)=f(7)+f(7)=7+7=14

f(xy) = f(x+y)
berarti,
f(49) = f(7 x 7) = f(7 + 7) = f(14)
sedangkan,
f(14) = f(2 x 7) = f(2+7) = f(9)
sedangkan,
f(9) = f(1 x 9) = f(1+9) =f(10)
sedangkan,
f(10) = f(2 x 5) = f(2+5) = f(7)

jadi, f(49) = f(7) = 7