# simplify

• December 17th 2007, 08:31 AM
Chez_
simplify
Hi how can i simplify 3a^3b multiplied by 4(ab)^2.

Also how can i factorise x^2-4 and x^2-5x+6

Thank you
• December 17th 2007, 08:40 AM
bobak
first one.

Rules of indices maybe? do you know them ?

difference of two square ?

have you never done a question like these before ?

• December 17th 2007, 08:41 AM
Simplicity
Quote:

Originally Posted by Chez_
Hi how can i simplify 3a^3b multiplied by 4(ab)^2.

Also how can i factorise x^2-4 and x^2-5x+6

Thank you

$3a^3b \times 4a^2b^2$
$=12a^5b^3$ (Constants are multiplied and the powers are added)

$x^2-4$ $=(x+2)(x-2)$
(This is difference of two squares e.g. $(x+a)(x-a)= x^2 - a^2$)

$x^2-5x+6$
$=(x-2)(x-3)$
(Here you have to see what two values can be used that allow us to obtain $6$ by multiplying and $-5$ by adding)
• December 17th 2007, 08:42 AM
colby2152
Quote:

Originally Posted by Chez_
Hi how can i simplify 3a^3b multiplied by 4(ab)^2.

Also how can i factorise x^2-4 and x^2-5x+6

Thank you

$3a^{3b}*4{ab}^2 = 12a^{2+3b}b^2$
Tip: Review over exponents in algebra

$x^2-4=(x-2)(x+2)$
Tip: When you need to factor a term like this, it is usually a multiplication of conjugates.

$x^2-5x+6=(x-3)(x-2)$
Tip: Look at the constant term and list all the ways you can multiply two numbers to equal it. Then find the pair of numbers that add up to the coefficient in the middle.

$ax^2+bx+c$

You want $(x+D)(x+E)$ where $D + E = b$ and $D*E=c$