Question

A company builds computers. It costs $6700 to build 10 computers and $12200 to build 20 computers. Which equation models the cost C(x), as a linear function of the number of computers built, x?

Answer 1

Possible answers:
A. C(x)=550x-1200
B. C(x)=550x+1200
C. C(x)=1200x-550
D. C(x)=1200x+550

Answer 2

@mathmale

Answer 3

@acxbox22

Answer 4

Daniel, this problem is much like the previous one. You are given two points on a straight line (which may not be immediately obvious); you need to find the equation of this line, doing exactly what we did last time. The two points are (10, $6700) and (20, $12200). Do you see why? Please find the slope of the line passing thru these two points.

Answer 5

Once you've done that, we'll solve your equation for y, which will also be the desired function, C(x).

Answer 6

m=550

Answer 7

y-6700=550(x-10)

Answer 8

y-6700=550x-5500

Answer 9

This looks appropriate, so I'm not going to check the math (yet).

Just add $6,700 to both sides of your equation. What do you get?

Answer 10

y=550+1200

Answer 11

That was easy

Answer 12

Daniel, let's check your result. Steal one of the two points. Substitute its x into your formula. Does the resulting y agree with the y-coordinate of your point?

Answer 13

6700=550(10)+1200

Answer 14

6700=5500+1200

Answer 15

Is that what you'd expected? If x=10, y=$6,700?

Answer 16

6700=6700

Answer 17

Yes

Answer 18

Great. Sure looks promising!

Now rewrite your equation by substituting the label C(x) for y.

What do you get?

Answer 19

C(x)=550x+1200

Answer 20

Got it... thank you

Answer 21

Got it! That's your desired formula!
Cool!
I need to get off the 'Net now, but very much look forward to working with you again soon! All the best to you, as always.

Answer 22

I also need to leave... Same to you