How do I use the substitution method when one equation doesn’t have a slope?

Answer 1

Hi Bella,

The substitution method still works for example

if the first equation is say y=5x+2 and the second equation is y=4 (no slope)

To solve you would substitute for y in the first equation giving 4=5x+2 and solve for x=2/5.

So the solution is (2/5,4)

If you think of these problems graphically it becomes clear. The first equation has a y intercept of 2 and a slope of 5 so it slopes upward toward the right. the second equation is just a horizontal line at y=5. Where the two lines intersect is the solution.

Hope this helps

Jim