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19 votes
19 votes
determine the equation of the line that is parallel to the given line (y=-5x+1), through the given point (-2,3)

User Mike Holler
by
3.0k points

1 Answer

15 votes
15 votes

Answer:

y=-5x-7

Explanation:

For lines to be parallel with one another, that means they have to have the same slope. The slope of this equation is -5

From there we have to find the b (or the y-intercept) of the new equation. To do this we plug in the slope and the x and y from the given point (-2,3) into the equation y=mx+b and solve for b:

3=-5(-2)+b

3=10+b

-7=b

Finally, we make a new equation with the b (-7) and slope (-5):

y=-5x-7

DON'T READ IF YOU DON'T WANT TO/ALREADY KNOW HOW TO DO THIS FOR A LINE PERPENDICULAR TO THE GIVEN LINE:

To find a line perpendicular to (y=-5x+1), you do everything the same as before but instead of using -5 as the slope for your new equation (including the one you use for solving for the new b) you use it's negative reciprocal. That basically means you switch the numbers numerator and denominator and switch the sign. Remember, every whole number has a denominator of 1, so it'll look like this:

-5/1 turns into 1/5

Then you use 1/5 as the slope for the new equation by plugging in the x and y of the given point and solving for b like we did before. Finally you take the 1/5 as the slope and the b you solved for and put those into a equation like you did before and bam.

If you're confused after reading that then forget everything I said.

hope this helps :D

User Hardik Modha
by
2.6k points