Question

Write the equation of the line that passes through the point (2,−1) and has a slope of 3.

Answer 1

Answer:

(-2,3) and has a slope of 1/2

Point-slope formula is...

y-y1=m(x-x1)

m is slope.

y-3=(1/2)(x--2)

y-3=(1/2)(x+2)

y-3=(1/2)x+1

Add 3 to both sides...

3+y-3=(1/2)x+1+3

y=(1/2)x+4

This is slope-intercept form...

y=mx+b

m is the slope.

b is the y-intercept, the value of y when x=0.

If you would like this in standard form...

Ax+By=C, A>0

y=(1/2)x+4

Let's subtract (1/2)x from both sides...

-(1/2)x+y=(1/2)x-(1/2)x+4

-(1/2)x+y=4

Bearing in mind the fact that A must be greater than zero, let's multiply both sides by -1...

-1[-(1/2)x+y]=(4)(-1)

(1/2)x-y=-4