Question

Which equation has a graph that contains points that slant downward, left to right, and crosses the y-axis at y =4?
a. x + y = -4
b. y - x = -4
c. y - x = 4
d. x + y = 4
@iambatman @TheSmartOne

Answer 1

@iambatman I was going to post the question on the previous post, but it somehow did not work.

Answer 2

So if the y-intercept is 4 then the line must have (0,4) as as solution...

Answer 3

And A and D look the same...

Answer 4

Do you know of the form y = mx+b? This is initially dealing with such a line. It's called the slope intercept form. Try seeing if you can put it in such a way and graph it out using some points.

Answer 5

What is y = mx + b ?

Answer 6

And how does this relate to the answer choices?

Answer 7

Can someone please help me right now? I need to finish my homework.

Answer 8

@TheSmartOne I can't really get what you are trying to say by saying that A and D look the same.

Answer 9

Well A & D are exactly the same...

Answer 10

Sorry that was my typo. A has -4 as the sum

Answer 11

ok lol

Answer 12

well we coul first plug in (0,4) and see which ones it works for and elimnate 2 answer choices.

Answer 13

could*

Answer 14

So you mean 0 for x and 4 for y right?

Answer 15

Yes.

Answer 16

Okay so will it be D, then?

Answer 17

Because if the y-intercept is 4 then that means x=0 and then y=4.

Answer 18

When you plug that in you should get 2 choices... And then from there we can use the second peice of inf they gave us.

Answer 19

So is it not D because if x =0 and y=4, then 0+4=4?

Answer 20

@TheSmartOne

Answer 21

It is D because 0+4=4 4=4 but there is 1 more answer choice

Answer 22

C?

Answer 23

So it is Both C and D so far.. Now we need to use the second piece of informaton.

Answer 24

Here is a graph of C and D.
https://www.desmos.com/calculator/istu6qhknf
Now which one slants downward @calculusxy @~

Answer 25

What do mean by the "second piece of information?"

Answer 26

slants downward means a negative slope

Answer 27

Do you mean to say "left to right?"

Answer 28

1st piece of information: slants downward
2nd piece of information: y-intercept is 4

Answer 29

The sum should be -4?

Answer 30

their sum should be 4... remember 0+4=4 and 4-0=4

Answer 31

slope is negative or slants downward means the line should be like this

Answer 32

so how do we narrow from C and D

Answer 33

i am not too good with slopes so i am having a problem...sorry if i am causing any disturbances :(

Answer 34

well C has a positive slope and d has a negative slope...

Answer 35

Here is the graph..
https://www.desmos.com/calculator/nhzcgep8lo

Answer 36

SO it definitely ahs to be D.

Answer 37

So*

Answer 38

Thank you so much!