If 4x+2y=16 and 6x-2y=4 , find the value of (y-x).
MATHEMATICS
WAEC 2021
If 4x+2y=16 and 6x-2y=4 , find the value of (y-x).
- A. 8
- B. 2
- C. 4
- D. 6
Correct Answer: B. 2
Explanation
Using elimination method:
4x+2y=16 * 6 --> 24x +12y=96 ... eqn iii
6x-2y=4 * 4 --> 24x - 8y = 16 ... eqn iv
Subtract eqn iv from iii
20y = 80
y = 4
Subst. y for 4 in 4x + 2y = 16
--> 4x + 2(4) = 16
--> 4x = 16 - 8
--> 4x = 8
--> x = 2
: The value of (y-x) is 4 - 2 = 2
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