Question

For what value of a do the lines 5x–2y=3 and x+y=a intersect at a point on the y-axis?

Answer 1

So what they are trying to say is that they both have the same y-intercept. Easy!

Make y the subject:

5x - 2y = 3

2y = 5x - 3

y = 2.5x - 1.5

The y-intercept is -1.5.

Make y the subject:

x + y = a

y = -x + a

Therefore, a must be -1.5 !