(-1,-2)(4,-5)
asked May 19, 2015

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## 2 Answers

find the equation of the line that passes through (-1,-2)(4,-5)

Start by finding the slope, which can be determined by the
numbers given.

P1    (x1, y1)     (-1, -2)
P2    (x2, y2)     (4, -5)
slope m = (y2 - y1) / (x2 - x1)
m = (-5 - (-2)) / (4 - (-1))
m = (-5 + 2) / (4 + 1)
m = -3 / 5

We now have enough information to find the y-intercept, b.

y = mx + b
y - mx = b

We'll use P2 for this.

b = -5 - ((-3/5) * 4)
b = -5 - (-12/5)  = -5 + (12/5)

Here, we will change the -5 into a fraction.

b = (-25/5) + 12/5)  = -13/5

With the slope and the intercept known, we write the general equation:

y = (-3/5)x - 13/5

Test them with P1. We know x1 = -1; find y1.

y = (-3/5)(-1) - 13/5
y = 3/5 - 13/5 = -10/5 = -2

Verified.
answered May 19, 2015 by Level 11 User (78,600 points)

Given (x1,y1) and (x2,y2) =(-1,-2) and (4,-5)
m = y2-y1/x2-x1
m = -5+2/4+1
m = -3/5

y= mx+c
-1=(-3/5)(-2)+c
c= -11/5
y=(-3/5)x--11/5

Trigonometry Help Online

answered May 27, 2015 by Level 8 User (30,400 points)

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