Question

Determine the x so that the three points (x, -3), (9, 1) and (13, 2) will lie on a straight line.

Answer 1

Answer:

x = -7

Step-by-step explanation:

Let A(x,-3) B(9,1) and C(13,2) lie on a straight line

Then, the slope for AB (m1) = the slope for AC (m2)

Let us calculate:

m1= (1+3)/(9-x) = (4)/(9-x)

m2 = (2+3)/(13-x) = (5)/(13-x)

m1 = m2

==> (4)/(9-x) = (5)/(13-x)

Cross multiply:

==> 52-4x = 45-5x

==> x = -7