SOLUTION: HOW DO U FIND THE SLOPE AND Y-INTERCEPT OF A LINE WRITTEN IN THE Y-FORM?

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Question 73232: HOW DO U FIND THE SLOPE AND Y-INTERCEPT OF A LINE WRITTEN IN THE Y-FORM?
Answer by checkley75(3666) About Me  (Show Source):
You can put this solution on YOUR website!
Y=mX+b IS THE LINE FORMULA WHERE X&Y ARE A SET OF POINTS, m=SLOPE & b=THE Y INTERCEPT.
IF YOU HAVE A SLOPE & A POINT YOU CAN FIND THE Y INTERCEPT THUS:
POINT IS (2,-4) & THE SLOPE IS 2. NOW SUBSTITUTE THESE FACTS AND SOLVE FOR THE Y INTERCEPT(b)
-4=2*2+b
-4=4+b
b=-4-4
b=-8 SO THE EQUATION OF THIS LINE IS
Y=2X-8
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ANOTHER APPROACH IS IF YOU HAVE TWO SETS OF POINTS (-1,3) & (3,-5).
YOU FIRST NEED TO FIND THE SLOPE THUS:
(Y2-Y1)/X2-X1)
(-5-3)/(3+1)
-8/4
-2 IS THE SLOPE OF A LINE THROUGH THESE TWO SETS OF POINTS.
NOW USE THE SLOPE & ONE SET OF POINTS & SOLVE FOR THE Y INTERCEPTtHUS:
3=-2*-1+b
3=2+b
b=3-2
b=1 SO THE LINE EQUATION IS
Y=-2X+1
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HERE ARE THE PLOTS OF THESE TWO EXAMPLES:
+graph%28+300%2C+200%2C+-6%2C+5%2C+-10%2C+10%2C+y+=+2x+-8%2C+y+=+-2x+%2B1%29+ (graph 300x200 pixels, x from -6 to 5, y from -10 to 10, of TWO functions y = 2x -8 and y = -2x +1).