Question

Use elimination to solve this system of equations x-4y=11 5x-7y=-10

Answer 1

First, isolate x in x-4y=11 because 1 is x's coefficient.
x-4y=11
x=11+4y
Now, substitute 4y+11 for x in 5x-7y=-10.
5x-7y=-10
5(4y+11)-7y=-10
20y+55-7y=-10
Add all coefficients.
13y+55=-10
Isolate y by subtracting 55 from both sides.
13y+55=-10
13y=-10-55
13y=-65
y=-5
Now substitute -5 for y in your first equation.
x=11+4y
x=11+4(-5)
x=11-20
x=-9
Your answer would be (-9,-5).
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