What is an equation in slope-intercept form of the line that is perpendicular to the graph of y=2x+3 and passes through (3, -4)?

1 Answer
Jun 13, 2018

y=-1/2x-5/2

Explanation:

The slope of the line perpendicular to the graph of y=2x+3 is -1/2. The perpendicular slope is the negative inverse of the original slope. The product of perpendicular slopes is -1, where:

m_1m_2=-1,

where:

m_1 is the original slope (2) and m_2 is the perpendicular slope.

2m_2=-1

Divide both sides by 2.

m_2=-1/2

So we now have the slope and we have been given a point (color(red)3,color(blue)(-4)).

Find the point-slope form of the perpendicular line.

y-y_1=m(x-x_1)

Plug in the known values.

y-(color(blue)(-4))=-1/2(x-color(red)3)

y+4=-1/2(x-3) larr point-slope form.

To convert the point-slope form to slope-intercept form, solve the point-slope form for y.

Slope-intercept form is: y=mx+b, where m is the slope and b is the y-intercept.

y+4=-1/2(x-3)

y+4=-1/2x+3/2

Subtract 4 from both sides.j

y=-1/2x+3/2-4

Multiply 4 by 2/2 to get an equivalent fraction with 2 as the denominator.

y=-1/2x+3/2-4xx2/2

Simplify.

y=-1/2x+3/2-8/2

Simplify.

y=-1/2x-5/2 larr perpendicular slope-intercept form

graph{(y-2x-3)(y+1/2x+5/2)=0 [-11.25, 11.25, -5.625, 5.625]}