Question

Se $\left[\begin{array}{ccc}3&2&\\1&4&\\&&\end{array}\right] . \left[\begin{array}{ccc}a&1&\\-2&b&\\&&\end{array}\right] = \left[\begin{array}{ccc}5&7&\\-5&9&\\&&\end{array}\right]$ então A + B é igual a:
a)3
b)5
c)7
d)9
e)10

Answer 1

3a+2.(-2)=5
3a-4=5
3a=5+4
a=9/3
a=3

3+2b=7
2b=7-3
2b=4
b=4/2
b=2
então a+b=2+3=5