the function of x f(x)=4x-7
a) f(3)
b) f(-5)

the teacher told my son a) was the right answer. Why? If I can understand how to solve, I can help him.

thanks,

ginger wages

It's easier than you think. Just plug in the values.

f(3)=4(3)-7=12

That's all you do. Plug them in and see what you get.

Quote:

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Originally Posted by ginwages

the function of x f(x)=4x-7
a) f(3)
b) f(-5)

the teacher told my son a) was the right answer. why? if i can understand how to solve, i can help him.

thanks,

ginger wages

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thanks. Then why not -5? Because in my brain
f(-5)=4(-5)-7=-27

I don't understand why this is a wrong answer and 3 is a right answer
HELLLPPP!!

-20-7=-27. That's correct. How would anyone get 3 from that?

If it were f(5/2), then 3 would be the answer.

Quote:

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Originally Posted by ginwages

the function of x f(x)=4x-7
a) f(3)
b) f(-5)

the teacher told my son a) was the right answer.

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LOL I see where your confusion is. You said a) was the right answer. But what you don't understand is that a) is the question!!

the question asks that you have an equation f(x) = 4x - 7 and it wants you to find the value when x = 3 which is part a) and when x = - 5 which is -27.

so the answers are as follows
a) f(3) = 4x-7 = 4(3) - 7 = 5
b) f(-5) = 4x - 7 = 4(-5) - 7 = -27


P.S. Galactus the answer to f(3) = 5 NOT 12

Yes, I see. A typo/brain fart.

Quote:

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Originally Posted by cool_dude

LOL i see where your confusion is. you said a) was the right answer. but what you don't understand is that a) is the question!!!

the question asks that you have an equation f(x) = 4x - 7 and it wants you to find the value when x = 3 which is part a) and when x = - 5 which is -27.

so the answers are as follows
a) f(3) = 4x-7 = 4(3) - 7 = 5
b) f(-5) = 4x - 7 = 4(-5) - 7 = -27


P.S. Galactus the answer to f(3) = 5 NOT 12

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Wow, your smart! U helped me a lot! :eek:
I'm a student! I needed help on my homework, then I came across this! THANKS A lot! :D

Find the indicated value for the following function: f(x) = 3x + 6
Find where F(x) = 0

It would help terrifically a lot if you post your question in a new thread. I just spent time reading through all the above stuff just to find a completely different question. The more time we waste doing that, the longer it takes us to help people.

If f(x) = 0, then 0 = 3x + 6. Then solve.

I have been going absolutely insane trying to figure out functions and graphing and YOU have taught me how to do functions and I just want to say THANK YOU! My own instructor could not do this. Do you tutor? ($)

Find the indicated value?
Find f(10) when f(x)=7x-3

Did you take a look at the previous answers? :rolleyes:

There is the method of how to solve your problem in there.

f(10) = 7*10 - 3 = 70 - 3 = 67