Question

A science experiment begins with a metal at -100° Celsius. The following function describes the temperature change per minute: f(x) = 89x - 100°. How will the graph of this function change if the metal is at 25° at the start of the experiment?

The line will shift vertically up by 125°.

The line will shift vertically up by 25°.

The line will shift vertically down by 125°.

The line will shift vertically down by 25°.

Answer 1

@anteater

Answer 2

Do you have an idea of which of these would be correct?

Answer 3

No, sorry. I'm having a really hard time with this one. /:

Answer 4

That's ok. For this problem, the slope of the line stays the same (89), but the y-intercept changes and is now at 25, rather than -100.

Answer 5

Just a moment, please. I think a drawing might help. :)

Answer 6

I realize that those lines don't really look like they have a slope of 89, since that would look a little steeper. I am artistically challenged. :)

Answer 7

Lol its ok I get the picture (:

Answer 8

But the idea is that before when x = 0, y = -100. And now, when x = 0, y = 25. But they didn't make any other changes to the line, so the slope stays the same and your new line is parallel to the old one.

Answer 9

So what direction has your line been shifted and by how much?

Answer 10

Look again. The new line is above the old one. :)

Answer 11

And each of the marks is 25 units. I should have written the scale.

Answer 12

Down by 5?

Answer 13

Up, actually. And the difference between 25 and -100 is 25 - (-100) = ?

Answer 14

Oh. 75??

Answer 15

-75 I mean.

Answer 16

Sorry, I don't think I know what I'm doing haha

Answer 17

Getting there :) When you subtract a negative number, remember it's the same as adding a positive number of the same magnitude. So 25 - (-100) = 25 + 100

Answer 18

So it's A?

Answer 19

Before when you noted that there was a difference of 5 spaces between -100 and 25, that was a good observation. Since each of the marks on the graph is worth 25, that would give you 5(25) = 125 :)

Answer 20

Yes :D

Answer 21

Ohh ok. Thank you soooo much!!

Answer 22

You're welcome! So in a linear function the number at the end tells you where the line crosses the y-axis (y-intercept). And, the number that is multiplied by x gives you the slope or steepness of the line.

Answer 23

And for this problem, they told you they were changing the y-intercept from -100 to 25, so that would give you a line above and parallel to the one they started out with. I hope that makes sense!

Answer 24

It does! Thanks! :D

Answer 25

Good! :)

Answer 26

Have you got any other questions?

Answer 27

No, that was all. And the one's you helped me on were both right! (:

Answer 28

Ok, good :) Have a good afternoon!!! :D