Write an equation in slope-intercept form for the line that satisfies each set of conditions.

Question

29. Passes through (-2,5) and (3,1)
I already figured out the slope which is -4/5, but I can't figure out how to calculate the y-intercept. Can someone help me?

Answer 1

You must know that the slope y-intercept form of the equation takes the form
y = mx + b
and you said that the slope is -4/5 , so you know the equation must be
y = (-4/5)x + b
Why not just sub in (3,1) ? Wouldn't that leave b as your unknown ???

Just for fun, also sub in (-2,5) and see what happens.

Answer 2

Wait, could you please explain the process of that. This is the part where I get really confused. My textbook didn't explain it well.

Answer 3

(-2, 5), (3,1 ).
m = (1-5)/(3-(-2)) = -4/5.

Y = mx + b.
5 = (-4/5)*(-2) + b.
b = ?.
.
Eq: Y = (-4/5)x + b(use calculated value of b).

Answer 4

That would mean that b= -17/5. So my final answer would be: y = -4/5x - 17/5.

Answer 5

Thank you both for all your help. I now understand how to do it. :')

Answer 6

Glad we could help!