sertai cara nya tlg..:)

12.
(5x-2)²
= (5x-2)(5x-2)
= 5x(5x) + 5x(-2) - 2(5x) -2(-2)
= 25x² - 10x - 10x + 4
= 25x²-20x+4 (C)

13.
x²-7x+12 = 0
x² - 4x - 3x + 12 = 0
x(x-4) - 3(x-4) = 0
(x-4)(x-3) = 0 (B)