Question 274704: Explain how you decide whether it is easier to solve a system by substitution or addition.
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! Explain how you decide whether it is easier to solve a system by substitution or addition.
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There is no general answer to that question.
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You could say if you have x or y with a coefficient
of one, substitution MAY be more practical.
Example:
x + 3y = 5
2x + 5y = 8
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Solve the 1st equation for "x:
x = 5-3y
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Substitute for "x" and solve for "y":
2(5-3y)+5y = 8
10 -6y + 5y = 8
-y = -2
y = 2
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Then substitute for y in x = 5-3y to solve for "x"
x = 5-3(2)
x = -1
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Solution: (-1,2)
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Cheers,
Stan H.
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