Question

what is the formula in slope-intercept form of a line that has a y-intercept of -2.5, intercepts the x-axis at 1, and has specific points (-2,-7) and (4,8)? give any fractions, if present in the formula, in simplified form.

Answer 1

Interpreting this as two separate lines:

1) Line with y-intercept -2.5 and x-intercept 1:
- y = (5/2)x - 5/2

(Reason: points (0,-5/2) and (1,0) give slope (0 - (-5/2))/(1 - 0) = 5/2.)

2) Line through (-2,-7) and (4,8):
- y = (5/2)x - 2

(Reason: slope = (8 - (-7))/(4 - (-2)) = 15/6 = 5/2; using (4,8) gives b = 8 - (5/2)*4 = -2.)