Question

Jika f(xy) = f(x-y) dan f(7) = 7, maka f(49) = ...?

Answer 1

F(xy) = f(x - y)
perhatikan bahwa :
f(7) = 7
f(7x1) = f(7-1) = f(6) = 7
dan
f(6) = f(3x2) = f(3 - 2) = f(1) = 7
sedangkan,
f(1) = f(1 x 1) = f(1 - 1) = f(0) = 7

maka, nilai dari :
f(49) = f(7 x 7) = f(7 - 7) = f(0) = 7