# algebra - expand - simplify - solve - rearrange help!

• Feb 10th 2009, 09:04 AM
gilzean
algebra - expand - simplify - solve - rearrange help!
can you show some workings too please that would be great :):)

1) (q+4)(q+5) expand and simplify i got - q(squared)+9q+20

simplified 9q(cubed) + 20

2) expand and simplify (2k - 3m)(3k+2m) help?

3) Solve 5(x+1)=3x + 12

4)facotorise x(squared) + 5x + 4

5) rearrange the forumla to make x the subject y = b- ax(squared)

5) solve x(squared) + 5x + 4 = 0
• Feb 10th 2009, 09:16 AM
mollymcf2009
Quote:

Originally Posted by gilzean
can you show some workings too please that would be great :):)

1) (q+4)(q+5) expand and simplify i got - q(squared)+9q+20

simplified 9q(cubed) + 20

You can't combine $q^2$ and $9q$, they have different powers (you multiplied them), leave it in the quadratic form
. By simplifying it means combine all your like terms, like 5q & 4 q

2) expand and simplify $(2k - 3m)(3k+2m)$ help?

F.O.I.L. First. Outer. Inner. Last

$6k^2 + 4km - 9km -6m$

$= 6k^2 - 5km -6$

3) Solve 5(x+1)=3x + 12

First, distribute your 5 through (x+1) to get 5x +5 = 3x + 12. Then solve for x

4)facotorise x(squared) + 5x + 4

What two numbers, when added together give you 5 AND when multiplied together give you 4? (x+1)(x+4) right?

5) solve x(squared) + 5x + 4 = 0

You will have two answers. See #4. You can either factor it like I did above or use the quadratic equation to get your answers.

Got it now?
• Feb 10th 2009, 09:18 AM
gilzean
i dont think so because they are year 11 maths questions :S and i think oyur doing complex stuff with them im confussseeed
• Feb 10th 2009, 09:19 AM
mollymcf2009
If this is for a high school algebra class, then this is pretty basic algebra. Not sure how else to explain it to you. What are you confused on?
• Feb 10th 2009, 09:21 AM
gilzean
(2k - 3m)(3k+2m) surely would be 6K(squared) - 2km - 6m
• Feb 10th 2009, 09:24 AM
gilzean
so..factorising x(squared) + 5x + 4 actually = what?
• Feb 10th 2009, 09:27 AM
gilzean
it would really really help if you wrote out the answer for eaccchh showing the working like i know u did for number one but the rest would help
• Feb 10th 2009, 09:28 AM
mollymcf2009
Quote:

Originally Posted by gilzean
(2k - 3m)(3k+2m) surely would be 6K(squared) - 2km - 6m

(2k-3m)(3k+2m)

FOIL
First: $(2k)(3k) = 6k^2$

Outer: $(2k)(2m) = 4km$

Inner: $(-3m)(3k) = -9km$

Last: $(-3m)(2m) = -6m^2$

$6k^2 + 4km - 9km -6m^2$

Combine like terms:

$6k^2 - 5km - 6m^2$

Sorry I left out the $m^2$ somewhere in my first post.

Is that more clear?
• Feb 10th 2009, 09:31 AM
mollymcf2009
Quote:

Originally Posted by gilzean
so..factorising x(squared) + 5x + 4 actually = what?

$x^2 + 5x + 4$

$(x+4)(x+1)$

$x = -4$ and $x = -1$

Factoring is the reverse of FOILing. FOIL gets rid of factors and puts it into quadratic form. Factoring is undoing FOIL.
• Feb 10th 2009, 09:32 AM
gilzean
thanks alot , **** i left out the = 0 , x(squared) + 5x + 4 = 0 does that matter?
• Feb 10th 2009, 09:39 AM
mollymcf2009
Quote:

Originally Posted by gilzean
thanks alot , **** i left out the = 0 , x(squared) + 5x + 4 = 0 does that matter?

Well if you don't have an equal sign, you aren't really solving it, you would just be evaluating it. So since you need to find an answer for "x", yes you should have that =0 in there.

Ok? Good job sticking with it!(Wink)