If the following system is to be solved using the addition method, by what constant should one of the?
equations be multiplied if the x terms are to drop out?
-4x – 3y = 3
-28x – 10 y = -7
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If you want to get rid of the x terms, what number would you multiply -4 by to get 0 when adding them together?
Multiply the first equation by -7 would give you 28x + 21y = -21.
When you add that to the second equation, x is elminated. so you’ll have 11y = -28.
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tip:
to eliminate the x terms, you make them
a. have the same constant, but different signs.
For example:
-4x: constsant = -4
-28x: constant = -28
so, you change (-4) into (+28) by mulitplying the constant (-4) with (-7)
-4x -3y = 3 (multipling by (-7))
+28x + 21y = – 21
+28x + 21y = – 21
-28x – 10 y = -7
—————————addd
+21y – 10y = -28
11y= -28
y = -28/11
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