# how to find the equation? (easy question)

• January 10th 2013, 06:23 AM
phyfreak
how to find the equation? (easy question)
A line passes through the point (6, -7) and has a slope of -2 . Write an equation for this line.
i think there was a formula for that but i forgot it
• January 10th 2013, 06:35 AM
TheRhino1987
Re: how to find the equation? (easy question)
Use the formula Y = mx + b
The point you gave us has values (x,y) and the slope you gave us is 'm'

Knowing this...
-7 = (-2)(6) + b
-7 = -12 + b
b = 5

Now we write out the formula using the y-intercept(b) we calculated

Y = -2x + 5
• January 10th 2013, 06:48 AM
Soroban
Re: how to find the equation? (easy question)
Hello, phyfreak!

Quote:

A line passes through the point (6, -7) and has a slope of -2 .
Write an equation for this line.
i think there was a formula for that, but i forgot it.

Point-Slope Formula

The line through the point $(x_1,y_1)$ and having the slope $m$,

. . has the equation: . $y - y_1 \:=\:m(x-x_1)$