Question

Write the equation of the line that passes through the points (-5, 21) and (4, -15) in standard form

Answer 1

y = -4x + 1

Explanation:

The line passes through points (-5,21) and (-4,15)

Slope(m) = change in y ÷ change in x

m =
`(-15 - 21)/(4 - -5)`

m =
`(-15 - 21)/(4 + 5)` = -36/9 = -4

Taking another point (x,y) on the line and comparing it with point (4,-15):

-4 =
`(y + 15)/(x - 4)`

Cross multiplying gives:

y + 15 = -4x + 16

y = -4x + 1