(x-3) pangkat 2 = (x-2) pangkat 2 min 5

(x-3)² = (x-2)²-5
(x-3)(x-3) =(x-2)(x-2)-5
x²-3x-3x+9 =x²-2x-2x+4-5
x²-6x+9 = x² -4x + 4 - 5
x²-x²-6x+4x+9-4-5
=-2x