Originally Posted by

**ADY** Help please

Im trying to evaluate the following, but not sure if i'm going wrong,could someone please check this.

Evaluating 2**A** + 3**B**

Where

$\displaystyle A = \left(\begin{array}{cc}3&7\\4&-1\\-5&2\end{array}\right)$ $\displaystyle B = \left(\begin{array}{cc}-5&-3\\10&6\end{array}\right)$

To evaluate i use the scalar multiplication?

so:

2**A **becomes = $\displaystyle \left(\begin{array}{cc}6&14\\8&-2\\-10&4\end{array}\right)$

and

3**B **becomes= $\displaystyle \left(\begin{array}{cc}-15&9\\30&18\end{array}\right)$

So my dillema is, i cant add these together can i because the incorrect rows to columns - or am i thinking this through to much?

Thanks for your help

Ady