Math help urgent.

[SImoHayha]

Nath

[Ekpyrosis]

binomial formula ...

(a- b )²=a²-2ab+b²

In this case a=3x and b=5.

edit: FU auto-emojis

[Virgule]

(g o h) (x) is basically taking g(x) and replacing x with h(x)

 

after that, it's simply a matter of simplifying

[colonel_mortis]

It comes from the expansion of the (3x-5)², which you expand using FOIL (if you haven't heard of that, never mind) - it expands to 3x*3x + 3x*-5 + -5*3x + -5*-5 (you can't just square each term - every term has to be multiplied by every other term), which simplifies to 9x² - 30x + 25. If you still don't follow that, I would advise asking your math(s) teacher, because expansion of brackets is a skill that you really need for the more advanced math(s) (though I can still try to explain it to you).

[SImoHayha]

(g o h) (x) is basically taking g(x) and replacing x with h(x)

 

after that, it's simply a matter of simplifying

I know that but my question is where is -30 is coming from. I know where 9x^2 and 25 is coming from.

[SImoHayha]

It comes from the expansion of the (3x-5)², which you expand using FOIL (if you haven't heard of that, never mind) - it expands to 3x*3x + 3x*-5 + -5*3x + -5*-5 (you can't just square each term - every term has to be multiplied by every other term), which simplifies to 9x² - 30x + 25. If you still don't follow that, I would advise asking your math(s) teacher, because expansion of brackets is a skill that you really need for the more advanced math(s) (though I can still try to explain it to you).

I LOVE YOU THANK GOD. I GET IT NOW. The only thing I wasn't aware of was 3x(-5) + -5(3x)

[Ekpyrosis]

I know that but my question is where is -30 is coming from. I know where 9x^2 and 25 is coming from.

The -30x comes from expanding (3x-5)². I think you are assuming that (3x-5)²=9x²-25. This, however is not the case.

You can't expand products of polynomials like that.

Maybe some concrete numbers can help you to understand this:

(2-1)² is obviously not equal to 2²-1².

Do you remember the binomial formulas? Or how to multiply out a product of two sums (remember that (3x-5)² is (3x-5)*(3x-5) )?

[SImoHayha]

The -30x comes from expanding (3x-5)². I think you are assuming that (3x-5)²=9x²-25. This, however is not the case.

You can't expand products of polynomials like that.

Maybe some concrete numbers can help you to understand this:

(2-1)² is obviously not equal to 2²-1².

Do you remember the binomial formulas? Or how to multiply out a product of two sums (remember that (3x-5)² is (3x-5)*(3x-5) )?

That is what I forgot basically.  the (3x-5)^2  = (3x-5)*(3x-5)

[Toxic Tom]

Ok I'm fucking tripping balls

Why are you doing maths while you're tripping?