Question

heeeelp please! The equation of line LM is y = 5x + 4. Write an equation of a line perpendicular to line LM in slope-intercept form that contains point (−3, 2).

y = −5x + 13

y = negative 1 over 5x + 7 over 5

y = 1 over 5x − 7 over 5

y = 5x − 17

Answer 1

what do you know about the slopes of perpendicular lines?

Answer 2

yes ma'am

Answer 3

I just don't understand slope equations

Answer 4

In y = mx + b form, the m position is the slope. So look at your equation, y = 5x + 4, and tell me what the slope is

Answer 5

5
is the slope

Answer 6

correct....however, we are looking for a perpendicular line. We need the negative reciprocal of the slope given. All that means is " flip " the slope, and change the sign. For example...you have a slope of 1/7 and you want the negative reciprocal of that slope. Flip the slope and change the sign. The negative reciprocal of 1/7 is -7/1. So what do you think the negative reciprocal of 5 (or 5/1) is ?

Answer 7

-5 or -5/1 right?

Answer 8

negative reciprocal of 5 (or 5/1) is -1/5...do you see how I flipped the slope and changed the sign ?

Answer 9

yes I do, thank you

Answer 10

so next I would...

Answer 11

we can now either use point slope formula--y - y1 = m(x - x1, or slope intercept formula--y = mx + b, to find the perpendicular equation. Which would you prefer to use

Answer 12

either one will give you the same answer...so which one do you want to use ?

Answer 13

hello ??

Answer 14

the second one seems less complicated lol

Answer 15

so --y = mx + b I guess

Answer 16

-y= -5/1 + 4 ?

Answer 17

true....slope intercept formula : y = mx + b

slope(m) = -1/5
(-3,2) x = -3 and y = 2
we already know the slope, so basically we will be solving for b (the y intercept)
Lets sub now...
y = mx + b
2 = -1/5(-3) + b -- distribute through the parenthesis
2 = 3/5 + b -- subtract 3/5 from each side
2 - 3/5 = b -- common denominator is 10
20/10 - 6/10 = b
14/10 = b
7/5 = b

so our equation is : y = -1/5x + 7/5

any questions ?

Answer 18

wow ive never understood this until now thank you so much! do you just answer these questions in your free time bc that's really nice of you!

Answer 19

I do not mind helping out....there might be a time when I need somebody to help me :)

Answer 20

well thanks again :)))

Answer 21

no problem :)

Answer 22

so do I do the same thing to this problem? The equation of line CD is y = −2x − 2. Write an equation of a line parallel to line CD in slope-intercept form that contains point (4, 5)

Answer 23

One thing you need to remember...when looking for perpendicular slope, you need the negative reciprocal of slope given. But when you need a parallel slope, the slope remains the same.

Answer 24

so what is the slope of the equation given ? Thats the first thing you need to find

Answer 25

remember, in y = mx + b form, the slope is in the m position. So do you know what the slope of y = -2x - 2 is ?

Answer 26

well its y= -2x-2

Answer 27

slope is -2

Answer 28

correct....and since we are looking for a parallel line, the slope will remain the same.
Now we can use y = mx + b form
slope(m) = -2
(4,5) x = 4 and y = 5
now sub and solve for b. Can you do that ?

Answer 29

so I make it 5=-2x(4)-2

Answer 30

or -b?

Answer 31

5 = -2(4) + b --- remember you subbed in 4 for x, so you do not need to list the variable x......and it is +b....because y = mx + b. Understand ?

Answer 32

yes yes I do

Answer 33

now can you finish and solve for b ?

Answer 34

leme try brb

Answer 35

does b=13

Answer 36

5 = -2(4) + b
5 = -8 + b
5 + 8 = b
13 = b

correct....now we know that the slope is -2....so our equation will be :
y = -2x + 13

Understand ?

Answer 37

yes! finally lolol thanks a million

Answer 38

sure thing...glad I could help :)

Answer 39

:)