Jawapan

2015-03-09T19:09:00+08:00
X + 4y - 3 = 0    ⇔    x = -4y + 3
x² + xy - 15 = 0
(-4y+3)² + (-4y+3) y - 15 = 0
16y² - 24y + 9 - 4y² + 3y - 15 = 0
16y² - 4y² - 24y + 3y - 15 + 9 = 0
12y² - 21y - 6 = 0
4y² - 7y - 2 = 0
(4y +1) (y - 2) = 0
y = 1/4
atau
y = 2