I really need help with this question on multiplying matrices, I've been stuck on it for over 20 minutes and I'm about to cry (ignore the 240 at the end, it's probably wrong)
so we mutiply the number of rows of the first matrix by the number of collumns of the second matrix
3*2 is the dimentions of the resulting matrix you have [tex]
\left[\begin{array}{cccc}9&4&8&6\\2&0&3&1\\1&-2&5&0\end{array}\right]
\left[\begin{array}{cc}12&2\\15&1\\3&9\\8&11\end{array}\right]
=[/tex][tex]\left[\begin{array}{cc}9*12+4*15+8*3+6*8&9*2+4*1+8*9+6*11\\2*12+0*15+3*3+1*8&2*2+0*1+3*9+1*11\\1*12+-2*15+5*3+0*8&1*2+-2*1+5*9+0*11\end{array}\right] [/tex]=[tex]\left[\begin{array}{cc}108+60+24+48&18+4+72+66\\24+0+9+8&4+0+27+11\\12+-30+15+0&2+-2+45+0\end{array}\right][/tex]=[tex]\left[\begin{array}{cc}240&160\\41&42\\-3&45\end{array}\right][/tex]
