Question

A line goes through the point (6,-2) and has a slope of -3. What is the value of a if the point (a,7) lies on the line?​

Answer 1

m = y1 - y2 / x1 x2

-3 = -2 - 7 / 6 - a

-3 = -9 / 6 - a

-3 (6 - a)=-9

-18 + 3a = -9

3a = - 9 + 18

a = 9 / 3

a = 3

Answer 2

a = 3

Explanation:

The slope of a line given two points can be found by using the formula

`m = ( y_2 - y _ 1)/(x_ 2 - x_ 1) \\`

From the question the slope is - 3

To find the value of a we have

`- 3 = (7 - - 2)/(a - 6) \\ - 3 = (7 + 2)/(a - 6) \\ - 3(a - 6) = 9 \\ - 3a + 18 = 9 \\ - 3a = 9 - 18 \\ - 3a = - 9`

Divide both sides by - 3

`( - 3a)/( - 3) = ( - 9)/( - 3) \\`

We have the final answer as

a = 3

Hope this helps you