# Algebra help please!

Printable View

• Sep 15th 2005, 09:30 PM
N00b
Algebra help please!
I've been having some problems with these, if someone could help that's be nice.

Perform the indicated operations and simplify.
x^2 - x - 6 x^2 - 3x - 4
x^2 + 4x + 3 * x^2 - 4x + 3

(Note: This was originally a division problem but I flipped the last fraction to make it multiplication as I think your suppose to, that and I didn't know how to type the division sign.)

Find the lowest common denominator:
5a - 15, 10a - 30

Solve the equation.
2 + x - 1 = x^2 - 1
x + 2 x + 3 x^2 + 5x + 6

Perform the indicated operations and simplify.
see attachment
• Sep 16th 2005, 12:41 AM
hoeltgman
If you factorize all the terms of your two fractions (it's easy since they are all second degre) You will see the you can simplify afterwards quite a lot.

Should be looking like this:

$\displaystyle \dfrac{(x+2)(x-3)}{(x+1)(x+3)} \cdot \dfrac{(x+1)(x-4)}{(x-1)(x-3)}$
This gives:
$\displaystyle \dfrac{(x+2)}{(x+3)} \cdot \dfrac{(x-4)}{(x-1)}$

5 should be the lowest common denominator. You can extract him out of both functions.

Start factorizing the term under the fraction of the right side. You will get (x+2)(x+3). Now multiplicate everything with that. All the fractions will disappear. Then you develop all the terms. And you will come back to an equation of the first degree. Answer should be -2/3.

For the last one, you have to put all the terms that arent on the fractions with (x-4) on these fractions. The you can switch to an multiplication by inversing one fraction. Finally you simplifie the second degrees and you look what's going to rest. Answer should be (x-2)/(2x-5).
• Sep 16th 2005, 06:19 AM
N00b
Thanks!

Although I think I typed the third one wrong.
see attachment
So if you could check it and see if that changed anything i'd be nice.
• Sep 16th 2005, 08:50 AM
hoeltgman
Well this one is different from the previous one, but the way it's done is identical. Just you get another result: x=-5/3