# Determine whether an equation determines y as a functions of x ### 94 thoughts on “Determine whether an equation determines y as a functions of x”

• September 13, 2012 at 10:32 pm

Just 1 question, if I have y^=(squareroot)x+2, which is similar to your second one. How would I know if that is a function or not

• September 13, 2012 at 10:39 pm

can you reprint that problem again this is what I think you are asking y^2 = sqrt(x+2)?
Is that it or what is the problem again?

• January 18, 2013 at 7:45 pm

so if it has a y^2 then it can't be a function of x?

• January 18, 2013 at 9:02 pm

correct

• January 24, 2013 at 3:30 am

thanks. Cleared that up for me on my math homework

• January 24, 2013 at 12:13 pm

• January 27, 2013 at 8:58 pm

• January 27, 2013 at 9:01 pm

• February 8, 2013 at 11:48 am

Yes! I have all the videos you should need in your class. Three years running making videos. Happy to help!

• February 26, 2013 at 4:32 am

Okay, Mr. McLogan, I have solved my equation. But, I still don't know or understand if it should be -y2 = -4x – 6; Therefore,﻿ y is not a function of x….OR should it be to solve the previous equation further and now say y=4x+6 and IS a function of x. Please help. I don't want to cheat. I just want to understand. I am SO LOST.

• February 26, 2013 at 11:54 am

• February 27, 2013 at 12:46 am

Determine whether the equation define y as a linear function of x. If so, write it in the form y=mx+b. 4x – 7y2 + 6 = 0; **the 7 is y to second power…exponent.

• February 27, 2013 at 11:58 am

okay since y is squared you will have to take the square root on both sides to undo the operation. Therefore leaving you with a positive and negative value of x. Y cannot be defined as a linear function of x. This can only be done when all exponents on variables are raised to the first power and no two variables are multiplied by each other or appear in the denominator. Does this help?

• May 31, 2013 at 7:50 pm

THANK YOU!!!!!!!!!!

• June 1, 2013 at 4:50 pm

you are welcome! happy to help.

• August 14, 2013 at 8:42 pm

So what if (on the second problem) the y isn't squared? Do you still use the square root and get a +- out of the answer?

• August 14, 2013 at 10:11 pm

no if it just y then the answer would be 8 since it is y squared we have to take the sqrt of both sides

• August 15, 2013 at 3:47 am

Where did the 8 come from?

• August 30, 2013 at 4:59 pm

On the first problem if you subtract x , could it be y= 9-x or does it have to be y= -x +9 … Thank you

• September 12, 2013 at 12:53 am

my favorite bald guy!!! u just saved me thanks so much!

• September 12, 2013 at 2:24 am

you had me a bald guy! : ) c'mon it's shaved head, there is no loss of hair. haha really happy to help you out. Keep up the hard work, bald man is a working.

• October 13, 2013 at 11:46 pm

Awesome!! I always get stuck on these problems!

• October 14, 2013 at 1:30 am

no worries, happy to help!

• October 23, 2013 at 7:04 pm

You explained to me in 3 minutes what my teacher couldn't in 2 hours, thank you!

• October 23, 2013 at 10:13 pm

you are very welcome! happy to help

• October 27, 2013 at 4:26 am

You look shy.. Didn't really understand it tho.. But knew what u were saying.. At least now I know alil about this math

• October 27, 2013 at 6:12 pm

Do you have a question I can help you with to better understand? Sometimes shy, sometimes not, depends on my mood i guess

• January 22, 2014 at 9:19 pm

So pretty much every time you have to use the square root then the answer will not be a function?

• July 6, 2014 at 7:45 pm

×=y^2+4 would not be a function?

• July 6, 2014 at 7:47 pm

what about x < 4y…how do I solve for that?

• August 19, 2014 at 4:19 am

thank you!

• August 21, 2014 at 8:33 pm

so if anything is y^2 or x^2 or anything squared, its not a function?

• September 2, 2014 at 7:17 pm

Oh, my goodness!!!!! Thank you so much!!!! You have no idea how much this helped me!!!! I'm in Trig and PreCalc and we just learned this today, and I had NO idea how to do it. It turns out that my math teacher taught us this same thing, just in a WAY more complicated way that I didn't understand at all. BUT, then I watched this, and I completely understand now!!!! THANK YOU SO MUCH!!!! You just saved my life 😀

• September 18, 2014 at 3:52 am

Hmmm I still dont understand T-T! Im going to fail my test tomorrow aaaahhh!!

• November 13, 2014 at 5:50 pm

What if the problem looks like this x+2y=6 help me workout help problem

• November 18, 2014 at 8:34 pm

god bless you u helped me alot

• February 25, 2015 at 12:07 pm

You should provide more examples than just the most basic ones.

2x-5y²=2
4|y| -5x²=2

• March 1, 2015 at 5:06 pm

thanks a lot m8 the video helped me, I have my algebra test in 2 days.

• April 22, 2015 at 1:01 am

PLZ HELP! I can't solve this problem. X=-y^2+2y+1 I can't find the y-value.

• June 23, 2015 at 3:48 am

Cool, Thank you!! 🙂

• August 29, 2015 at 3:46 am

• December 7, 2015 at 11:22 am

I'm pretty confused how is radical 4 equal to 2 and at the same time equal to 2 you didnt say the point only if there is "" out of the radical it becomes -2

• February 3, 2016 at 7:26 am

And what about the domain and range?

• February 16, 2016 at 4:12 am

Drink some water.

• February 26, 2016 at 5:51 am

Thank you! This made waaay more sense than when my professor explained it.

• June 20, 2016 at 3:20 pm

if y has an exponent of 3 is it still a function?

• June 26, 2016 at 6:39 am

OH MY GOD. THANK YOU THIS IS SO HELPFUL!!!

• September 13, 2016 at 4:09 am

This man has literally come to the rescue for me…a week late in college classes, you're the best man

• September 13, 2016 at 7:52 pm

is y=|x| a funtion?

• September 14, 2016 at 11:02 pm

Thank you. This helped me under understand this concept very easily

• October 31, 2016 at 3:54 am

would y=|4x-18| be a function? what about |y|=4x-18

• February 1, 2017 at 4:24 pm

Why does this make 0 sense to me

• February 5, 2017 at 10:01 pm

is y=√x+3 a function and why?

• June 13, 2017 at 11:15 am

Thank you! This actually helped me.

• August 23, 2017 at 1:28 am

Hello!I received two questions that say to determine y as a function of x (or not).
I'm attempting to solve these two and ran into some problems.

Well, the first question is y = x²  ±  3.
How would I go about solving the problem with a plus/minus sign? Does that mean I will have two answers? Do I solve it normally?

And the second question: x = 12 – y.
Would I subtract 12 as to get y alone? But, if I do, it will be "-y = x-12" Then how would I deal with that negative sign?

• September 6, 2017 at 12:35 am

Is y=x^3 a function and you can explain?

• September 10, 2017 at 7:12 pm

when you subtract x^2 on both sides won't you get plus minus i when you square root both sides?

• September 13, 2017 at 12:44 am

does this mean that anytime there is a exponent of 2 that it is not a function ?

• September 25, 2017 at 7:39 pm

The problem I'm working on is y=4x(squared)

I thought it wasn't a function because of the square after the X, but the answer key is saying that it's a function. I'm confused.

• October 11, 2017 at 1:05 am

I got a 45 on my test, but it would've been a 0 without your help. Thanks man

• November 28, 2017 at 9:46 pm

so basically what he meant was that everytime you have an y^2, it will not be a function because y is not allowed to be squared, only the x can.

• December 9, 2017 at 7:50 am

Is f(x)=x a function? Why?

• January 25, 2018 at 1:24 am

okay so YOU HELPED ME BIG TIME FOR THIS QUIZ BUT i dont get the f(x) crap for my practice problems if im solving for Y

• January 26, 2018 at 4:45 pm

Thank you! This helped a lot!

• January 31, 2018 at 6:43 pm

Thanks!

• February 1, 2018 at 2:30 pm

• February 6, 2018 at 10:44 pm

Thanks a lot, funny how my professor won't explain this as easy as you do.

• March 28, 2018 at 6:29 pm

thx fam

• July 1, 2018 at 2:03 pm

Thank You! 🙂

• August 19, 2018 at 9:09 pm

This teacher is litty 💯

• August 24, 2018 at 3:56 am

is 2x^2 + y^2 = 5 isnt a function right?

• August 25, 2018 at 2:48 am

Thanks a bunch!

• August 28, 2018 at 9:28 pm

Wait but what does y=3^x mean?

• September 4, 2018 at 2:27 am

• September 6, 2018 at 4:51 pm

im so confused by your example. given the square root or x^2+1 why can you not just take out the square root giving you x+1? it makes almost no sense to me that you would have to keep it the way it is. and also is that the case for a cubed root as well?

• September 15, 2018 at 10:44 am

X2-y2=?? PlZ😢♥

• September 19, 2018 at 12:48 am

Can y be raised to an odd power and be a function

• November 5, 2018 at 6:05 pm

In regards to the second equation, wouldn't the answer not exist? You dropped the negative in continuing to solve the equation. The square root would have been taken from -x^2 not x^2. Does this change the result?

• January 14, 2019 at 2:47 am

So x= any number
Is also not a “y is a function of x” answer?

• January 30, 2019 at 3:08 am

Thank you for the brief understanding.. really helpful..

• April 22, 2019 at 2:55 pm

So all in all, if it has 2 answers for y, then it's not a function of x

• June 17, 2019 at 2:11 pm

so it needs to be a one-to-one equation?

• August 21, 2019 at 1:02 am

But you can’t take the square root of the negative X

• August 22, 2019 at 3:10 am

You just saved me from a zero bih

• August 28, 2019 at 4:00 pm

What if its x + y^3 = 8? Is it a function?

• August 28, 2019 at 4:01 pm

So if y is ^ to any number does it mean its already not a function? Plsss answer i have an exam tomorrow and im really struggling😭

• September 7, 2019 at 4:00 pm

Please use darker markers! Good job!

• September 10, 2019 at 11:41 pm

God…

• September 25, 2019 at 6:45 pm

How many times has this man saved my life? Too many to count lol

• October 13, 2019 at 11:41 pm

Omshi thank you!

• October 24, 2019 at 7:13 pm

What allowed you to get rid of the -x +1 and make it x+1?????

• January 13, 2020 at 11:53 pm

what if y is a negative?

• January 17, 2020 at 2:03 am
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