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A line passes through the point (3, -6) and has a slope 2 of . Write an equation for this line.

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3 Answers

First, the problem tells us that the slope is 2, so from the equation

 y=m x + b

we know m=2. We have one more info that is not exploited, which we shall use to find "b":

-6 = 2 * (3) + b = 6 + b.

Hence 

b = -12. And all in all

y = 2 x - 12. Note the "-" sign to signify that "b" is negative.

Eme:

The standard equation for a straight line where the slope (m) is provided and a point on the line (x0, y0) is specified is (y-y0)=m(x-x0).  Substituting for m, x0, and y0 with the information provided, you get:

(y-(-6))=2(x-3)

Simplifying the above:  y+6=2x-6

or y=2x-12

y = mx + b

x = 3, y = -6, m = 2

-6 = 2(3) + b

-6 = 6 + b

-6 -6 = 6 - 6 + b

-12 = b

y = 2x - 12