Gimana nih caranya no 114?

9^(x-1) = (1/3)^(4x-1)
3^(2x-2) = 3^(1-4x)
2x - 2 = 1 - 4x
6x = 3
x = 1/2

f(y) = y² + 2xy + 4x²
f(y) = y² + 2(1/2) y + 4(1/2)²
f(y) = y² + y + 1
agar f(y) memiliki nilai paling kecil, maka y harus sama dengan 0

f(0) = (0)² + 0 + 1
f(0) = 1