Question

http://screencast.com/t/yPOxDocH

How is this incorrect?

Answer 1

you must have substituted incorrectly. No way to tell what you did wrong unless we see your work.

Answer 2

Actually, I think it's because I failed to distribute the "-" for the second input of g(x). Let me see

Answer 3

My apologies, I seem to have violated a rule by posting the solutions. Could you show or explain to us what steps you've taken first?

Answer 4

That is my work. Let me know if you need clarification

Answer 5

Awful quality...lol yeesh

Answer 6

For the portion which says (2x-4)(2x-4), under that does that say 2x^2 -8x -8x +16 ?

Answer 7

Here is a better quality picture.

Answer 8

2x(2x)=4x^2

Answer 9

Try checking your FOIL again :] just a simple error.

Answer 10

Mertsj has pointed it out.

Answer 11

Ah I'm dumb...I'm awful with exponent rules...thank you for that. :)

Answer 12

yw. You'll get it now.

Answer 13

We all make simple mistakes! Let us know your final solutions and see if the software your class uses will accept that.

Answer 14

I will! Final question, was my constant correct? 6?

Answer 15

Should be 16+4-6

Answer 16

Or would I distribute the negative and get a constant of 14?

Answer 17

Okay, thank you!

Answer 18

Whenever there is a minus sign infront of brackets, imagine a negative one (-1) instead an multiply it into each term inside.

Answer 19

Could I suggest a simpler solution?

Answer 20

Ah, says incorrect :c http://screencast.com/t/3ML6ee7wLkxk

Answer 21

Replace 2x-4 with y and your equation becomes:
\[y^2-y-6=0\]

Answer 22

Could you factor and solve that equation?

Answer 23

I'm not sure where to start

Answer 24

factor

Answer 25

Factor it like you would if those y's were x's.

Answer 26

(y-3)(y+2)=0

Answer 27

Now set each factor equal to 0 and solve for y

Answer 28

Are you having any difficulties?

Answer 29

So x=3 and 2?

Answer 30

in this case while we still go on Mertsj's method, it would be y = 2, 3. It is important to distinguish that it is y (or any other letter other than x) in this case because we are temporarily letting y = (or represent) 2x-4

Answer 31

Now that you have figured out y = 3 and y= -2 you can resub the original function in. Put back what we called y (which is 2x-4) back into the equation.

btw: it is 3 and -2 not just 2. I made a typo in the previous reply.

Answer 32

Anyways to continue, 2x-4 = 3 and 2x-4 = -2 is what you should get when you resubstitute back in. Hopefully you understand why we are allowed to resub and call 2x-4 "y" variable.

Now solve for x in those two equations.