SOLUTION: Find the value of r so that the line through (-4,3) and (r, -3) has a slope of 2/3.

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Question 122076: Find the value of r so that the line through (-4,3) and (r, -3) has a slope of 2/3.
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
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Find the value of r so that the line through (-4,3) and (r, -3) has a slope of 2/3.
:
Using the slope formula; %28y2-y1%29%2F%28x2-x1%29 = m
Assign the values as follows:
x1 = -4; y1 = 3
x2 = r; y2 = -3
m = 2%2F3
:
%28-3+-+3%29%2F%28r+-+%28-4%29%29 = 2%2F3
%28-6%29%2F%28%28r%2B4%29%29 = 2%2F3
Cross multiply
:
2(r+4) = -6(3)
:
2r + 8 = -18
:
2r = -18 - 8
:
r = %28-26%29%2F2
r = -13
:
:
Check by finding the slope using x2 = -13
%28-6%29%2F%28%28-13%2B4%29%29 =
%28-6%29%2F%28-9%29 = +2%2F3