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write the equation of the line passing through the points (-2,4) and (1,-5) in slope intercept form.?
2 Answers
- RaymondLv 72 months agoFavorite Answer
slope-intercept format looks like this:
y = mx + c
where m and c are usually numbers, and where
m is the slope = how fast y rises, when x goes up by 1,
c is the y-intercept (the value of y, when x=0)
In an ordered pair, the coordinates are given in the order of (x, y)
for these points, x goes from -2 to + 1 (an increase of +3)
while y goes from 4 to -5 (a "rise" of -9 -- in other words, a decrease)
The slope is, therefore, -9/3 = -3
Every time x goes up by 1, y goes DOWN by 3.
m = -3
So far, we have
y = -3x + c
To find the value of c, we simply pick one point
say (x, y) = (-2, 4)
We use these values in the equation, and solve for c
y = -3x + c
becomes
4 = -3(-2) + c
4 = 6 + c
-2 = c
We now have everything we need. We put it all together
y = mx + c
is now
y = -3x - 2
We check this with the other point (x, y) = (1, -5)
-5 = -3(1) - 2
-5 = -3 - 2
TRUE
- az_lenderLv 72 months ago
m = (4 - (-5))/(-2 - 1) = -3, so
y = -3x + b, where b is found from
(4) = -3(-2) + b => b = -2.
Answer: y = -3x - 2.