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Question 5 (5 points)

Find the equation of the line passing through the point (-1, 5) and perpendicular to
the line y=-3x+4.
A) 3y=-x+16
B) 3y=x+16
OC) y=-3x+8
D) y=-3x+2
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User Windor C
by
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1 Answer

29 votes
29 votes

Answer:

Option B is perpendicular to y=-3x+4 and goes through point (-1,5)

Explanation:

We will look for an equation of the form y=mx+b, where m is the slope and b the y-intercept. The reference line, y=-3x+4, has a slope of -3. A line perpendicular to this line will have a slope that is the "negative inverse" of the refence lines slope. In this case, it's slope would be +(1/3).

We could graph each of the equation options and look for one that is perpendicular, but it might be faster to simply rearrnaged the options into standard format of y=mx+b. which we'll do here:

Option Rearranged Equation Slope

A) 3y=-x+16

y = -(1/3)x+(16/3) -(1/3)

B) 3y=x+16

y = (1/3)x + (16/3) (1/3)

C) y=-3x+8 -3

D) y=-3x+2 -3

There is only one option that has the required slope to be parallel to the reference equation (y=-3x+4), option B: y = (1/3)x + (16/3)

Does it go through point (-1,5)?

y = (1/3)x + (16/3)

Enter x = -1 and find 5:

y = (1/3)(-1) + (16/3)

y = (16/3)-(1/3)

y = (15/3) or 5

Yes, it goes through point (-1,5)

Option B is perpendicular to y=-3x+4 and goes through point (-1,5).

User Denys
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