Question

A line passes through the point (–2, 7) and has a slope of –5. What is the value of a if the point (a, 2) is also on the line?

A.–7
B.–1
C.1
D.7

Answer 1

The answer is B.

Explanation:

Answer 2

The correct option is B.

Explanation:

The slope of a line is constant.

If a line passes through two points then the slope of the line is

`m=(y_2-y_1)/(x_2-x_1)`

It is given that the line passes through (-2,7) and (a,2).

Using the above formula the slope of the line is

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

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

It is given that the slope of the line is -5. Substitute m=-5 in the above equation.

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

On cross multiplication we get

`-5(a+2)=-5`

Divide both sides by -5.

`a+2=1`

Subtract 2 from both the sides.

`a=1-2`

`a=-1`

The value of a is -1. Therefore the correct option is B.