GRE Quant Ep 15: Functions & Intimidating Symbols

[@mohamedskallon6781]

All GRE NINJA videos have very good teaching strategies. Thank you GRE NINJA. Happy to come across your channel

[@hasansaleem4983]

good video, i got 3 out of 7 answers correct, but i learned a lot

[@hasansaleem4983]

thanks dude, you are an awesome teacher

[@omonefeehimen2794]

16:06 Hello, @GreNinja. It's great work you're doing here, very helpful. I'm just a bit confused by question 3. When we evaluate option D, f(-×) gives us -x(x²-2),I understand that. Doesn't multiplying the whole expression by a negative ( to get -f(-x)), give us x(-x²+2), which is not what we started with (x(x²-2)). Please explain further, thank you. And the same question for option E,thanks.

[@GRENinjaTutoring]

If we consider -x(x^2 -2), this is the same as saying (-1)x(x^2 - 2). If we multiply the whole expression by (-1), we could write this as (-1)(-1)x(x^2 - 2). The two (-1)s would multiply to give (1), so we could write the new expression as (1)x(x^2 - 2) which would simplify to x(x^2 - 2). In order to get x(-x^2 + 2), we would need to multiply our expression by another -1 to change the sign of everything inside that set of parentheses. However, we're only multiplying f(-x) by one -1 to give us -f(-x) so we won't get to x(-x^2 + 2). I'd make the same argument for (E) as I have for (D). I hope that helps, but please let me know if you have any further questions!

[@maureenudofia8328]

Thank you for the clarification.@@GRENinjaTutoring

[@omonefeehimen2794]

@@GRENinjaTutoring Thank you!

[@Jaydoe08]

Can you kindly explain the quadratics in the final question please.

[@yessbenne5924]

if a problem has must in it only get shoose the anwer you can be sure about from the elements u have

[@calculator5555]

Yes

[@mohamedskallon6781]

This is more than helpful thank you sir

[@hasansaleem4983]

for the last question, i just inserted all the options in (3p) and the value of that into f(x), this way i got the correct answers, but hey, using quadratic equation is good too!

[@smilykena9144]

Thank you very much. However, I don’t know how did you end up with -7 and 2, since 2-7= -5. Even if 7*-2= -14, there is still the a+b condition to fill for the quadratic equation. Isn’t it? I hope you see and answer my question please 🙏.

[@hasansaleem4983]

@@smilykena9144 hey, haha time goes fast! now i am not preparing for gre and as for your question, lemme check that, i wrote it in one of my books if i find it

[@hasansaleem4983]

@@smilykena9144 i found the answer! so the thing is, i did not use quadratic equation, rather i just substituted all the answer choices into '3p' then the following result into f(x)=x^2-x. Since x=3p here, so i got the correct answer choices which were a and c.