Question

Are the lines y = –x – 4 and 5x + 5y = 20 perpendicular? Explain.

Yes; their slopes are equal.
Yes; their slopes have product –1.
No; their slopes are not equal.
No; their slopes are not opposite reciprocals.

Answer 1

what are their slopes?

Answer 2

they dont give me that

Answer 3

the equations give you that information ... which tells me that you are not familiar with the basics of this material ....

Answer 4

so explain

Answer 5

If an equation has the form y = mx + c, m is the slope.

Answer 6

slope is the measure of the change in y values as a ration to the change in the x values ... the most basic way to find the slope is to define x as 0 and get the y value; then define x as 1 and get the y value and see what the difference between the y values are

Answer 7

y = –x – 4 ; when x=0, what does y =?

Answer 8

right

Answer 9

-0-4=

Answer 10

-4

Answer 11

good; and:

y = –x – 4 ; when x=1?

Answer 12

-5 :)

Answer 13

good :) now we want to know the change that happens in y from -4 to -5;

-5-(-4) = ?

Answer 14

-1

Answer 15

tha tis correct; so our slope of (y = –x – 4) is: -1

Answer 16

same process with the other equation:

5x + 5y = 20 ; when x=0, y has to equal what?

Answer 17

3?

Answer 18

because u subtract on both sides

Answer 19

and then you get 5y=15

Answer 20

and divide

Answer 21

good thinking there, just needs some practice to get better; but the process your thinking of should go like this:

5(0) + 5y = 20

0 + 5y = 20

5y = 20

y = ?

Answer 22

4 :) oh i see what i did wrong

Answer 23

correct :)

what you were thinking was ahead of the curve when x=1 we get:

5(1) +5y = 20

5 +5y = 20
-5 -5
-------------
0 +5y = 15

5y = 15

y = ?

Answer 24

3 :)

Answer 25

so y moves in this equation from 4 to 3

4 + m = 3

m = 3-4 = ?

Answer 26

? huh? lol it has 2 eqals?

Answer 27

its just read as m equals 3-4; so 3-4 = ? when everything equals each other like that you can simply write it out as such

Answer 28

m = 3-4

3-4 = ?

m = ?

Answer 29

m= 3-4

Answer 30

good; and 3-4 is equal to what?

3 -4 = ?

Answer 31

m :)

Answer 32

lol ... yes, but what what does "m" equal when we actually subtract 4 from 3?

Answer 33

ooooh lol 1 lol

Answer 34

3-4 = -1 ; all assume that was a typo :)

so if you recall what we started with, finding slopes we determined that

y=-x -4 ; has a change in y values of -1; it has a slope of -1

5x + 5y = 20; has a change in y values of -1; it too has a slope of -1


when 2 lines are going in the same directions; are they parallel or perpendicular?

Answer 35

they are parallel

Answer 36

very good :)

Since they are parallel, then they are definitely NOT perpendicular

Yes; their slopes are equal. <-- NOT the answer
Yes; their slopes have product –1. <-- NOT the answer

Which leaves us with 2 possibilitites

No; their slopes are not equal.
No; their slopes are not opposite reciprocals.

Answer 37

No; their slopes are not equal. <-- NOT the answer because they HAVE equal slopes

No; their slopes are not opposite reciprocals. <-- MUST be the answer since its the
only one left :)

Answer 38

rights :) wow this helped alot!!

Answer 39

im glad it did :)