x+2y=9 2x-5y=-33
Chapter 6 test
1) x + 2y = 9
2) 2x - 5y = -33
Multiply equation 1 by 2.
2 * (x + 2y) = 9 * 2
3) 2x + 4y = 18
Subtract equation 2 from equation 3, eliminating the x.
2x + 4y = 18
-(2x - 5y = -33)
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9y = 51
9y = 51
y = 51/9 = 5 2/3
Using equation 1, solve for x.
x + 2y = 9
x + 2(51/9) = 9
x + 102/9 = 9
x + 102/9 = 9
x = 9 - 102/9
x = -21/9
Check.
x + 2y = 9
-21/9 + 2(51/9) = 9
81/9 = 9
9 = 9
2x - 5y = -33
2(-21/9) - 5(51/9) = -33
-42/9 - 255/9 = -33
-297/9 = -33
-33 = -33
Answer: x = -21/9, y = 51/9