garis 4x-3y=10 menyinggung lingkaran : x^2+y^2+6x-2y=15 di titik...

4x - 3y = 10 => 4x = 3y + 10 => x = (3y + 10)/4
x^2 + y^2 + 6x - 2y = 15
((3y + 10)/4)^2 + y^2 + 6(3y + 10)/4 - 2y = 15
(9y^2 + 60y + 100)/16 + y^2 + (18y + 60)/4 - 2y = 15 ===> kali 16
9y^2 + 60y + 100 + 16y^2 + 72y + 240 - 32y = 240
25y^2 + 100y + 100 = 0
y^2 + 4y + 4 = 0
(y + 2)(y + 2) = 0
y = -2
x = (3y + 10)/4 = (3(-2) + 10)/4 = 4/4 = 1
Jadi titik singgungnya (1, -2)