## missashleyn Group Title Someone please help? Let f(x) = x2 – 16. Find f–1(x). one year ago one year ago

1. missashleyn Group Title

2. amistre64 Group Title

if we solve the problem: y = x^2 - 16; for x, what does it look like?

3. amistre64 Group Title

and technically, there is no inverse function stated in the choices :/

4. missashleyn Group Title

I have no idea :(

5. amistre64 Group Title

we need to remember how to manipulate equation around to solve for a particular variable: y = x^2 - 16 this can be algebrated about to solve for x

6. missashleyn Group Title

What would I do first?

7. amistre64 Group Title

would you agree that we can subtract 16 from each side to start to get x all alone?

8. amistre64 Group Title

err, add 16 to each side that is

9. missashleyn Group Title

Yes so it would be y = x^2/16? So C?

10. amistre64 Group Title

y = x^2 - 16 +16 +16 ---------------- y+16 = x^2 its not C, I havent gotten to the end results yet .....

11. amistre64 Group Title

do you know how we can get the "^2" off the x?

12. missashleyn Group Title

Multiply it?

13. amistre64 Group Title

good attempt, but lets try to take the square root, or sqrt it sqrt(y+16) = sqrt(x^2) sqrt(y+16) = x this is the general construct of our inverse function we are looking for, but they like to then swap xs and ys

14. missashleyn Group Title

Ohhhhh so it's B then?

15. amistre64 Group Title

B seems the most reasonable answer to me :)

16. missashleyn Group Title

Okay thank you! I have one more like this, could you help me with it too?

17. amistre64 Group Title

i can take a look at it sure

18. missashleyn Group Title

Let f(x) = 5x + 12. Find f–1(x).

19. amistre64 Group Title

lets try the same process, but this one is simpler since we aint got to sqrt nothing y = 5x + 12 how do we solve for x so that x is all alone on one side of the equation?

20. missashleyn Group Title

- 12 from each side y = 5x + 12 - 12 - 12 y - 12 = 5x

21. amistre64 Group Title

so far so good, now to uncover the x, we should divide off that pesky looking 5 right?

22. missashleyn Group Title

Yes so.. y - 12 = 5x ---------- 5 y - 12/5 = x

23. missashleyn Group Title

I think I'm confusing myself

24. amistre64 Group Title

you did fine, lets just make sure its looks "proper" :) $\frac{y-12}{5}=x$

25. missashleyn Group Title

Okay the closest choice I have to that is |dw:1360095933270:dw|

26. amistre64 Group Title

that will work fine ;)

27. amistre64 Group Title

good luck

28. missashleyn Group Title

Okay awesome, thank you!! :)