Question

The points (4, 1) and (x, -6) lie on the same line. If the slope of the line is 1 what is the value of x?

A -3
b 3
c 9
d 11

Answer 1

the unknown X value is -3

Explanation:

Let's determine X using the formula for the slope of a straight line, which

is m = (change in y) / (change in x). In this particular case, going from (4, 1) to (X, -6), the change in x is (X - 4) and the change in y is -6 - 1, or -7. Thus,

the slope m is:

-7

m = 1 = ----------

X - 4

And so: 1(X - 4) = -7, or X - 4 = -7, or X = -3

-7

Check: Does m = -4 = ------------ = 1 as specified in the problem statement?

-3 - 4 YES

So the unknown X value is -3.