# Math Help - Epanding expressions

1. ## Epanding expressions

Hi guys any ideas on how I would expand and collect like terms when it comes to these?

1. (2 + 3x)^3

2. (6 - 2y)(4x + 1) + 10xy - 2

3. Originally Posted by komodo
Hi guys any ideas on how I would expand and collect like terms when it comes to these?

1. (2 + 3x)^3

2. (6 - 2y)(4x + 1) + 10xy - 2

What have you tried? Where are you stuck?

1. (2 + 3x)(2 + 3x)(2 + 3x) = (Expand first two brackets)(2 + 3x) = .......

Simple Polynomial Multiplication

4. I tried to use the FOIL method with no success for the 1st question I got 4+6x+6x+9x^2 after multipliying the first two brackets...am I doing it wrong?

Thanks

5. Originally Posted by komodo
I tried to use the FOIL method with no success for the 1st question I got 4+6x+6x+9x^2 after multipliying the first two brackets...am I doing it wrong?

Thanks
No, that's good so far. You can simplify this to $9x^2+12x+4$

So to finish, you need to calculate $(9x^2+12x+4)(2+3x)$. Writing this as:
$2(9x^2+12x+4)+3x(9x^2+12x+4)$ may help.

6. Originally Posted by Quacky
No, that's good so far. You can simplify this to $9x^2+12x+4$

So to finish, you need to calculate $(9x^2+12x+4)(2+3x)$. Writing this as:
$2(9x^2+12x+4)+3x(9x^2+12x+4)$ may help.
Thanks mate that gives me 54x^2 + 36x + 27x^3 + 8 .....is this correct?

For the second question should I FOIL the brackets first then add the other values or is there another method that has to used?

Thanks

7. Originally Posted by komodo
Thanks mate that gives me 54x^2 + 36x + 27x^3 + 8 .....is this correct?

For the second question should I FOIL the brackets first then add the other values or is there another method that has to used?

Thanks
Looks good to me. For the second, just FOIL the brackets first and then collect like terms.

Edit: My only suggestion is to order your terms, starting with those containing the highest exponent. So write it as $27x^3+54x^2+36x+8$

8. Thanks guys much appreciated