Problem: solve the equations using elimination
solve the following equations using elimination x-2y=-1 and 2x+y=4
1) x - 2y = -1
2) 2x + y = 4
Multiply equation 2 by 2.
2(2x + y) = 4 * 2
3) 4x + 2y = 8
Add equation 1 to equation 3, eliminating the y term.
4x + 2y = 8
+(x - 2y = -1)
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5x = 7
5x = 7
x = 7/5
Use equation 1 to solve for y.
x - 2y = -1
7/5 - 2y = -1
7/5 - 2y - 7/5 = -1 - 7/5
-2y = -5/5 - 7/5
-2y = -12/5
-2y/-2 = (-12/5)/-2
y = (-12/5)(-1/2)
y = 12/10
y = 6/5
Use equation 2 to check the values.
4x + 2y = 8
4(7/5) + 2(6/5) = 8
28/5 + 12/5 = 8
40/5 = 8
8 = 8
Answer: x = 7/5, y = 6/5