posted by kim on .
find an equation of the line that passes through the points
The first one is
slope = y1-y2/x1-x2
slope = m = (0-5/0+1 = -5
y = mx + b
Then put in one of the points to calculate b.
5 = -5(-1) + b
5 = 5 + b
b = 0
So the line is
y= mx + b
y = -5x + 0 or y = -5x.
The other one is don the same way.
Check my work very carefully.
is the other problem is
The first pair is very very easy.
Remember that a line that passes through the origin must be of the form:
y = mx
since the intercept is zero. You are told that this line passes through the origin and that the point (-1, 5) satisfies the equation. You should be able to write the answerdown from there.
There are a couple of ways to do the second one. he two-point formula is
(y - y1) / (x - x1) = (y2 - y1) / (x2 -x1)
(y - 1) / (x - 2) = (-3 - 1) / (0 - 2)
(y - 1) / (x - 2) = 2
multiply across by x - 2
y -1 = 2x - 4
and you should be close enough to finish from there.