Question

Which equation represents the line passing through the points (1, 4) and (−2, 13)?

3x + y = 7
3x − y = 7
x − 3y = 7
x + 3y = 7

Answer 1

I can help here.

Answer 2

Okay, thanks. :)

Answer 3

The points are always given as (x,y). Do you know that?

Answer 4

Yes.

Answer 5

This says that when x is 1, then y is 4. We can check right?

Answer 6

Right.

Answer 7

Let's start checking with the first equation and see if it is satisfied.

Answer 8

The first one is right.

Answer 9

\(\Large \color{MidnightBlue}{\Rightarrow3(1) + 4 = 7 }\)
\(\Large \color{MidnightBlue}{\Rightarrow 3 + 4 = 7 }\)
\(\Large \color{MidnightBlue}{\Rightarrow 7 = 7 }\)
Stage one is complete.

Answer 10

Yes, it is correct :D

Answer 11

Thanks for talking me through that. :) Think you could help me with another one?

Answer 12

\(\Large \color{MidnightBlue}{\Rightarrow 3(-2) + 13 = 7 }\)
\(\Large \color{MidnightBlue}{\Rightarrow -6 + 13 = 7 }\)
\(\Large \color{MidnightBlue}{\Rightarrow 7 = 7 }\)

\(\Huge \checkmark\)

Answer 13

And sure!

Answer 14

Awesome. :)

A company builds computers. It costs $7,600 to build 10 computers and $12,200 to build 20 computers. Which equation models the cost, C(x), as a linear function of the number of computers built, x?

C(x) = 460x − 3000
C(x) = 3000x − 460
C(x) = 460x + 3000
C(x) = 3000x + 460

Answer 15

You can again check here.

Answer 16

Okay.

Answer 17

How would I go about that?

Answer 18

I see that the third one is correct.

Answer 19

Would I fill in the cost for C(x)?

Answer 20

Thank you. :)

Answer 21

Well, you see that 10 computers cost 7600, so you can see --> 460 * 10 + 3000 = 7600

Answer 22

Thanks so much! ♥