SOLUTION: Choose the equation in slope-intercept form for the line passing through each pair of points. (–1, 3) and (2, –5)

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Question 394758: Choose the equation in slope-intercept form for the line passing through each pair of points.
(–1, 3) and (2, –5)
Found 2 solutions by ewatrrr, josmiceli:
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!


Hi

Using the point-slope formula, m+=%28y%5B2%5D+-+y%5B1%5D%29%2F%28x%5B2%5D+-+x%5B1%5D%29 to find slope

(–1, 3) and 

(2, –5)   m = 3  -(-5) /-1-2 = 8/-3  Slope m = -(8/3)

the standard slope-intercept form for an equation of a lineis: y = mx + b  

where m is the slope and b the y-intercept.  

y = -(8/3)x + b    | using ordered pair Pt(-1,3) to solve for b

3 = 8/3 + b

1/3 = b

y = -(8/3)x + 1/3

Note: as y increases/decreases by 8, x value changes by 3 in the opposite direction

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
The slope will be (change in y)/(change in x)
m+=+%28-5+-+3%29%2F%282+-+%28-1%29%29
m+=+-8%2F3
The slope-intercept form is y+=+mx+%2B+b
So far I have y+=+%28-8%2F3%29%2Ax+%2B+b
If I substitute (-1,3) in the equation:
3+=+%28-8%2F3%29%2A%28-1%29+%2B+b
3+=+8%2F3+%2B+b
b+=+9%2F3+-+8%2F3
b+=+1%2F3
The equation is:
y+=+%28-8%2F3%29%2Ax+%2B+1%2F3
check:
does it go through (2,-5) ?
-5+=+%28-8%2F3%29%2A2+%2B+1%2F3
-15+=+-16+%2B+1
-15+=+-15
OK