WAEC - Mathematics (2011 - No. 4)
Solve the equation; 3x - 2y = 7, x + 2y = -3
x = 1, y = -2
x = 1, y = 3
x = -2, y = -1
x = 4, y = -3
Explanation
3x - 2y = 7; Solve by elimination method
x + 2y = -3
3x - 2y = 7.....(i)
-3x + 6y = -9.....(ii)
-8y = 16
y = \(\frac{16}{-8} = -2\)
Put y = -2 into equation (i); 3x - 2y = 7
3x - 2(-2) = 7
3x + 4 = 7
3x = 7 - 4
3x = 3
x = \(\frac{3}{3}\) = 1
x + 2y = -3
3x - 2y = 7.....(i)
-3x + 6y = -9.....(ii)
-8y = 16
y = \(\frac{16}{-8} = -2\)
Put y = -2 into equation (i); 3x - 2y = 7
3x - 2(-2) = 7
3x + 4 = 7
3x = 7 - 4
3x = 3
x = \(\frac{3}{3}\) = 1
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