Find the value of x and y respectively if 3x – 5y + 5 = 0 and 4x – 7y + 8 = 0
-
A.
-5, -4 -
B.
-4,. -5 -
C.
4, 5 -
D.
5, 4
Correct Answer: Option D
Explanation
3x – 5y + 5 = 0 → eqn1
4x – 7y + 8 = 0 → eqn2
eqn1 * 4; 12x – 20y + 20 = 0 → eqn3
eqn2 * 3; 12x – 21y + 24 = 0 → eqn4
eqn3 – eqn4 = y – 4 = 0
∴ y = 4
From eqn1,
3x – 5y + 5 = 0
3x – 5(4) + 5 = 0
3x – 20 + 5 = 0
3x – 15 = 0
3x = 15
x = 5
x and y = 5, 4 respectively