# Math Help - Binomial

1. ## Binomial

Binomial expansion -

(3x-2)^4

thanks

2. Originally Posted by gracey
Binomial expansion -

(3x-2)^4

thanks
Substitute (3x), (-2) and n = 4 into the binomial theorem formula. Where exactly are you stuck?

3. The binomial theorem:

$(x + y)^n = \displaystyle\sum_{k=0}^{n} \left(\begin{array}{cc}n\\k\end{array}\right) x^{(n-k)} y^k$

$\left(\begin{array}{cc}n\\k\end{array}\right) = \dfrac{n!}{k!(n-k)!}$

Just plug the values in and go.

4. Originally Posted by RubyRed
The binomial theorem:

$(x + y)^n = \displaystyle\sum_{k=0}^{n} \left(\begin{array}{cc}n\\k\end{array}\right) x^{(n-k)} y^k$

$\left(\begin{array}{cc}n\\k\end{array}\right) = \dfrac{n!}{k!(n-k)!}$ Just plug the values in and go.
I find it more useful to use the symbols A and B since x is often used with a different meaning in questions (like the one posted here) .....

$(A + B)^n = \displaystyle\sum_{k=0}^{n} \left(\begin{array}{cc}n\\k\end{array}\right) A^{(n-k)} B^k$.