Question 87497
Solve each system by substitution, if possible. If a system is inconsistent or if the equations are dependent, so indicate.
2x-y=-21
4x+5y=7
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Multiply the 1st equation by 2 to get:
4x-2y = -42
Subtract from 4x+5y=7 to get:
7y = 49
y = 7
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Substitue to solve for x, as follows:
2x-7 = -21
2x = -14
x=-7
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Solution: x=-7; y=7
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Solve the system of equations using the addition (elimination) method.
-7x+y=8
2x-y=2 
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Add the two equations to eliminate the y terms:
-5x = 10
x = -2
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Substitute and solve for y, as follows:
-7*-2+y=8
y=-6
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Check in the other equation:
-7*-2+-6 = 8
8=8
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Cheers,
Stan H.