## KrystaRenee What is the graph of the function? y = 2 · 2^x one year ago one year ago

1. KrystaRenee

First option.

2. KrystaRenee

Second option.

3. KrystaRenee

Third option.

4. KrystaRenee

Fourth option.

6. whpalmer4

Pick a few points and plot them. x = -1, x = 0, x = 1, x = 2 ought to tell you all you need to know, and are easy to compute here. Don't use a graphing calculator or WolframAlpha until you actually know how to do the work yourself, or you'll be up the proverbial creek without a paddle the first time you need to do one yourself.

7. KrystaRenee

I did and I got the third option, I believe.

8. whpalmer4

Oh, I hope not. Let's make a table: x y -1 2*(2^-1) = 2*1/2 = 1 0 2*2^0 = 2*1 = 2 1 2*2^1 = 2*2 = 4 2 2*2^2 = 2*4 = 8 Look at those graphs again.

9. whpalmer4

Just from a quick glance it ought to be apparent that as x increases, y gets big really fast. You're doubling y with each increase of 1 in x. There's no negative sign in front of it, so the curve goes up, not down.

10. whpalmer4

That leaves only the first two as possible contenders, and the plots we did appear on both, so we can see if the curve goes through them or not.

11. whpalmer4

12. whpalmer4

the points we did, not the plots we did, sorry

13. KrystaRenee

The second option?

14. whpalmer4

Does the curve on the second option go through the point (2,8)? If not, it cannot be the correct choice.

15. KrystaRenee

Damn it. I guess not. The first option does though.

16. whpalmer4

Yep!