Question 28975: a line that passes through the point (-1,3) has a slope of 2. find onother point on the line.
Answer by sdmmadam@yahoo.com(530)   (Show Source):
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a line that passes through the point (-1,3) has a slope of 2. find onother point on the line.
Given slope and a point we use the slope and point formula to give the equation.
The slope and point formula is given by
(y-y1)/(x-x1) = m ----(*) where m is the slope and P(x1,y1) is the given point
Here P(x1,y1)=P(-1,3) and m =2
Therefore the required line is (using (*))
[y-(3)]/[x-(-1)]= 2
(y-3)/(x+1)=2
Multiplying by (x+1) through out,
y-3=2(x+1)
y-3 = 2x +2
0=2x-y+2+3 (taking all the terms from the left to the right, change side,then change sign)
0=2x-y+5
Answer: The required equation is 2x-y+5 = 0
Verification: putx = -1 and y = 3 in the above.
LHS = 2x-y+5 =2X(-1)-3+5 = -2-3+5 =0=RHS
Therefore our equation is correct.
Note:How is 0=2x-y+5 represented as
2x-y+5 = 0
Why sign has not been changed?
Answer:The equality relation is symmetric. That is p = q implies and is implied by q = p
Only one or two or three (...)terms transaction from one side to another side then change sign
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