Question

−3x + 7y = −16

−9x + 5y = 16
Which equations should be multiplied and by what number?

please help ty

Answer 1

x=-4

y=-4

Explanation:

add -12x+12y=0

12y=12x

y=x

substitute in first eq.

-3x+7x=-16

4x=-16

x=-16/4=-4

y=x=-4

Or

multiply first eq. by -3

9x-21y=48

-9x+5y=16

add

-16y=64

y=64/-16=-4

substitute in first eq.

-3x+7(-4)=-16

-3x-28=-16

-3x=-16+28

-3x=12

x=12/-3=-4

so x=-4

y=-4

Answer 2

The first equation should be multiplied by -3

Explanation:

If you multiply the first equation by -3, then you can cancel out the 9x's in both equations by adding them together, leaving only the y's. Hope this helps!