Question

Solve the system of equations -2x-9y=8−2x−9y=8 and -5x-8y=-9−5x−8y=−9 by combining the equations.

Answer 1

(5,-2)

Explanation:

−2x−9y=8 (1)

-5x-8y=-9 (2)

5(1) - 2(2)

-10x - 45y = 40

10x + 16y = 18

-28y =58

y = -2

−2x−9(-2)=8

-2x = -10

x = 5

Answer 2

x= 5, y = -2

Explanation:

-2x-9y=8

-5x-8y=-9

Multiply the first equation by 5

5( -2x-9y)=8*5

-10x -45y = 40

Multiply the second equation by -2

-2 (-5x-8y)=-9*-2

10x +16y = 18

Add the new equations together to eliminate x

-10x -45y = 40

10x +16y = 18

--------------------------

-29y = 58

Divide each side by -29

-29y/-29 = 58/-29

y = -2

Now we can find x

-2x-9y=8

-2x -9(-2) =8

-2x +18 = 8

Subtract 18 from each side

-2x+18-18 = 8-18

-2x = -10

Divide by -2

-2x/-2 = -10/-2

x = 5