Question

identify an equation in point slope form for the line perpendicular to y=3x+5 that passes through (4,-1)

Answer 1

The equation in point slope form for the line perpendicular to y=3x+5 that passes through (4,-1) is y = -⅓x + ⅓

Explanation:

Given

Let P represent the lind

Equation of P; y = 3x + 5

Let Q represent the other point.

Coordinates of Q; Q(4,-1)

It is said that the line P is perpendicular to point Q.

So, the first thing to do is to calculate the slope of Q;

Since both lines are perpendicular, then we make use of formula for calculating the condition of perpendicularity

This is given as m1m2 = -1

Where m1 = slope of P

m2 = slope of Q

To get m1;

m1 is the coefficient of x in equation of line P.

So, m1 = 3.

Now we can solve for m2

m1.m2 = -1. ---- make m2 the subject of formula

m2 = -1/m1

Substitute 3 for m1

m2 = -1/3

m2 = -⅓

Recall that the coordinates of Q is 4 and -1.

To calculate the equation of Q; we make use of the following

m = (y - y1)/(x - x1)

Where m = m2 = -⅓

x1 = 4 and y1 = -1

By substituton, we have

-⅓ = (y - (-1))/(x - 4)

-⅓ = (y + 1)/(x - 4) --- multiply both sides by 3(x - 4)

-⅓ * 3(x - 4) = 3(x - 4) * (y + 1)/(x - 4)

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

-x + 4 = 3y + 3 --- make y the subject of formula

3y = -x + 4 - 3

3y = -x + 1 --- divide through by 3

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

y = -x/3 + 1/3

y = -⅓x + ⅓

Hence, the equation in point slope form for the line perpendicular to y=3x+5 that passes through (4,-1) is y = -⅓x + ⅓

Answer 2

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

Explanation:

We need to identify the equation in point slope form.

The standard equation of point slope form is:

(y-y₁) = m (x-x₁)

where m is the slope and x₁ and y₁ are the points

We are given point(4,-1) so,

x₁=4 and y₁=-1

And a perpendicular line: y =3x+5

Which is equal to y = mx+b

where m is slope so, slope m = 3

Since the line is perpendicular, so the slope in negative inverse of actual slope that m = -1/m

i.e, m = -1/3

So, the equation in point slope form is:

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

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