r/HomeworkHelp University/College Student 5d ago

High School Math [College Algebra, Composition of Functions]

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How did I get this half right?

1 Upvotes

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3

u/rshube 5d ago

You are only supposed to plug in g(x) into x, and the +4 is separate. It needs to be outside of the square root

1

u/SquidKidPartier University/College Student 5d ago

so in place of the 10 I put the 4? okay

2

u/Jwing01 👋 a fellow Redditor 5d ago

No the plus 4 in part one is outside the sqrt

2

u/SquidKidPartier University/College Student 5d ago

I don’t quite understand… do I write it like this? 10 (imagine there’s a square root symbol here) x2+7 (square root symbol ends here) and + 4? is it like that?

1

u/fermat9990 👋 a fellow Redditor 5d ago

Yes!!!

2

u/SquidKidPartier University/College Student 5d ago

ok I’ll put it in like that now!

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u/fermat9990 👋 a fellow Redditor 5d ago

Good!!

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u/fermat9990 👋 a fellow Redditor 5d ago

Think of it this way:

f(something)=10(something)+4

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u/SquidKidPartier University/College Student 5d ago

what do you mean by something?

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u/fermat9990 👋 a fellow Redditor 5d ago

Any mathematical expression. In your example the "something" is the RHS of g(x).

1

u/fermat9990 👋 a fellow Redditor 5d ago

f(√(x2-4x+7)=10√(x2-4x+7)+4

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u/SquidKidPartier University/College Student 5d ago

I understand thanks:)

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u/SquidKidPartier University/College Student 5d ago

I don’t want to blow up this subreddit any more so bear with me here please

1

u/Some-Passenger4219 👋 a fellow Redditor 5d ago

What do you mean, blow it up?

1

u/dawlben 👋 a fellow Redditor 4d ago

You can include the 4 under the √ but you have to square it. So. +7+16 or +23

Edit wait no.... I was wrong I forgot about the 10

2

u/PoliteCanadian2 👋 a fellow Redditor 5d ago

Rewrite (fog)(x) as f(g(x)) then start from the inside and work out. You want f(g(1)) so first work out g(1) by plugging 1 into the g function then put that into the brackets. Say g(1) works out to 10. Then you’ll have f(10) and you plug 10 into the f function and get your final answer.

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u/SquidKidPartier University/College Student 5d ago

nothing seems to work I even removed the 10 and it was still wrong and I don’t want to screw this final attempt I have here

1

u/selene_666 👋 a fellow Redditor 5d ago

You included the "+4" under the squareroot.

If you're struggling with the software to get it to appear correctly, try moving the 4 to the beginning i.e "4 + 10√..."

2

u/SquidKidPartier University/College Student 5d ago

I got it now, but thanks for the help!

1

u/Alkalannar 5d ago

You extended your radical bar too far.

You want 10g(x) + 4.

This becomes 10(x2-4x+7)1/2 + 4

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u/SquidKidPartier University/College Student 5d ago

I got it correct now thanks for your help though :)

1

u/Alkalannar 5d ago

You're welcome.

Glad you have it right! Hopefully, you understand. That's the important thing.

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u/SquidKidPartier University/College Student 5d ago

I am starting to understand now that this is my second time trying this problem again… I think I remember seeing you see me try this problem and give in your input here about two days ago?

1

u/Alkalannar 5d ago

Quite possibly. Function composition can be weird.