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Question 306868: Each set of three points is collinear. Find each missing x- or y-value. Enter each answer to the nearest hundredth.
(6, 10.2), (1.5, 3.45), (x, 2.85)
Answer by dabanfield(803)   (Show Source):
You can put this solution on YOUR website! (6, 10.2), (1.5, 3.45), (x, 2.85)
The slope-intercept form of a line is:
y = m*x + b where m is the slope and b is the value of y where the line crosses the x-axis (that is when x = 0 ).
m = (10.2 - 3.45)/(6 - 1.5)
m = 6.75/4.5 = 1.5
We have then
1.) y = 1.5*x + b.
Since the line passes through the point (6,10.2) when x = 6, y = 10.2. Substituting these values in 1.) we have:
10.2 = 1.5*6 + b
10.2 = 9 + b
b = 1.2
The equation of the line is then
2.) y = 1.5*x + 1.2
To find x for the third point on the line we substitute 2.85 for y in 2.):
2.85 = 1.5*x + 1.2
1.5*x = 2.85 - 1.2
1.5*x = 1.65
x = 1.65/1.5 = ?
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