WAEC - Mathematics (2007 - No. 29)
Solve the simultaneous equations x + y = 2 and 3x - 2y = 1
x = 2 and y = 1
x = 1 and y = 1
x = 1 and y = 2
x = -1 and y = 1
Explanation
x + y = 2........... (i)
3x - 2y = 1......(ii)
From (i): x = 2 - y ..........(iii)
subt. (2 - y) for x in (ii)
3(2 - y) 2y = 1
6 - 3y - 2y = 1
-5y = 1 - 6 = -5
y = \(\frac{-5}{-5}\) = 1
subst. (i) for y in (iii)
x = 2 - 1 = 1
x = 1, y = 1
3x - 2y = 1......(ii)
From (i): x = 2 - y ..........(iii)
subt. (2 - y) for x in (ii)
3(2 - y) 2y = 1
6 - 3y - 2y = 1
-5y = 1 - 6 = -5
y = \(\frac{-5}{-5}\) = 1
subst. (i) for y in (iii)
x = 2 - 1 = 1
x = 1, y = 1
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