Question

A line passes through the point (-2,7) and had a slope of -5

What is the value of a if the point (a,2) is also on the line
-7
-1
1
7

Answer 1

a = - 1

Explanation:

Calculate the slope m using the gradient formula

m = ( y₂ - y₁ ) / ( x₂ - x₁ )

with (x₁, y₁ ) = (- 2, 7) and (x₂, y₂ ) = (a, 2)

m =
`(2-7)/(a+2)` =
`(-5)/(a+2)` = - 5

multiply both sides by (a + 2)

- 5 = - 5(a + 2) ( divide both sides by - 5 )

1 = a + 2 ⇒ a = 1 - 2 = - 1