Question

Me ajudem a resolver isso.

Answer 1

$\left[\begin{array}{cc}3&2\\1&4\end{array}\right] . \left[\begin{array}{cc}a&1\\-2&b\end{array}\right] = \left[\begin{array}{cc}(3a-4)&(3+2b)\\(a-8)&(1+4b)\end{array}\right]$

3a - 4 = 5
a = 3

3 + 2b = 7
b = 2

a + b = 5

Resposta é a letra b.