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Question 58537This question is from textbook
: given these two points on a line, write the equation in slope-intercept form:
(5,-13) and (2,-1)
i did the coordinate approach and came out with: -1-(-13)/2-5=-4, which is the slope. to find the y=intercept, i took one of the points and did: 2=-4(-1)+b. I came out with 2=4+b. now subtracted 4 from both sides and got: 4-2=4+b-4 which simplifies to:-2=b. so my final equation would read: y=-4x+(-2). is this correct??
This question is from textbook
Found 2 solutions by funmath, checkley71:
Answer by funmath(2933)   (Show Source):
You can put this solution on YOUR website! You got the slope right, but when you substituted your point and slope into the slope intercept form to find b, you put the x coordinate where the y goes and the y coordinate where the x goes. m=-4, (x,y)=(2,-1)
-1=(-4)(2)+b
-1=-8+b
8-1=8-8+b
7=b
If you want to check your answer, use the other point (5,-13) to see if it's =.
-13=-4(5)+7
-13=-20+7
-13=-13 Looks like we're right!
Happy Calculating!!!
Answer by checkley71(8403) (Show Source):
You can put this solution on YOUR website! TO FIND THE SLOPE WE USE THE (Y2-Y1)/(X2-X1) VALUES THUS
(-1+13)/(2-5)=12/-3=-4 FOR THE SLOPE
THE FORMULA FOR THE LINE IS Y=mX+b
SO WE HAVE Y=-4X+b
NOW SUBSTITUTING EITHER SET OF POINTS FOR X AND Y WE GET THE VALUE b
-13=-4*5+b
-13=-20+b
-13+20=b
b=7
THUS THE FORMULA FOR THIS LINE THROUGH (5,-13)(2,-1) IS Y=-4X+7
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