X = -4
atau
X – 7 = 0
X = 7
b. Perhatikan cara di bawah ini:
2X2 – 5X – 12 = 0
(2X+3)(X-4) = 0
maka 2X + 3 = 0
2X = -3
X = –3⁄2
X – 4 = 0