SOLUTION: A line goes through the coordinate (3,4) and through (5,1). Find a line of the form y=ax+b.

Algebra ->  Graphs -> SOLUTION: A line goes through the coordinate (3,4) and through (5,1). Find a line of the form y=ax+b.      Log On


   



Question 112937This question is from textbook
: A line goes through the coordinate (3,4) and through (5,1). Find a line of the form y=ax+b. This question is from textbook

Found 2 solutions by jim_thompson5910, chitra:
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
First lets find the slope through the points (3,4) and (5,1)

m=%28y%5B2%5D-y%5B1%5D%29%2F%28x%5B2%5D-x%5B1%5D%29 Start with the slope formula (note: is the first point (3,4) and is the second point (5,1))

m=%281-4%29%2F%285-3%29 Plug in y%5B2%5D=1,y%5B1%5D=4,x%5B2%5D=5,x%5B1%5D=3 (these are the coordinates of given points)

m=+-3%2F2 Subtract the terms in the numerator 1-4 to get -3. Subtract the terms in the denominator 5-3 to get 2

So the slope is
m=-3%2F2

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Now let's use the point-slope formula to find the equation of the line:



------Point-Slope Formula------
y-y%5B1%5D=m%28x-x%5B1%5D%29 where m is the slope, and is one of the given points

So lets use the Point-Slope Formula to find the equation of the line

y-4=%28-3%2F2%29%28x-3%29 Plug in m=-3%2F2, x%5B1%5D=3, and y%5B1%5D=4 (these values are given)


y-4=%28-3%2F2%29x%2B%28-3%2F2%29%28-3%29 Distribute -3%2F2

y-4=%28-3%2F2%29x%2B9%2F2 Multiply -3%2F2 and -3 to get 9%2F2

y=%28-3%2F2%29x%2B9%2F2%2B4 Add 4 to both sides to isolate y

y=%28-3%2F2%29x%2B17%2F2 Combine like terms 9%2F2 and 4 to get 17%2F2 (note: if you need help with combining fractions, check out this solver)


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Answer:


So the equation of the line which goes through the points (3,4) and (5,1) is:y=%28-3%2F2%29x%2B17%2F2

The equation is now in y=mx%2Bb form (which is slope-intercept form) where the slope is m=-3%2F2 and the y-intercept is b=17%2F2

Notice if we graph the equation y=%28-3%2F2%29x%2B17%2F2 and plot the points (3,4) and (5,1), we get this: (note: if you need help with graphing, check out this solver)

Graph of y=%28-3%2F2%29x%2B17%2F2 through the points (3,4) and (5,1)

Notice how the two points lie on the line. This graphically verifies our answer.

Answer by
chitra(359) About Me  (Show Source):
You can put this solution on YOUR website!
The line equation passing through two points in the slope intercept form is given by:

%28+y+-+y1%29+=+m+%28x+-+x1%29 which is nothing but y = ax + b

Where m = %28y2+-+y1%29%2F%28x2+-+x1%29 (3, 4) and (5, 1)

m = %281+-+4%29%2F%285+-+3%29

==> m = -3%2F2

Substituting in the line equation we get:

(y - 4) = -3%2F2 (x - 3)

==> 2y - 8 = -3x + 9

==> 2y = -3x + 9 + 8

==> 2y = - 3x + 17

==> y = +%28-3%2F2%29x+%2B+%2817%2F2%29+

thus the line equation

Hence, the solution