Question

ME AJUDEMM se$\left[\begin{array}{ccc}3&&-1\\&&\\1&&1\end{array}\right] . \left[\begin{array}{ccc}&x&\\&&\\&y&\end{array}\right] = 4 . \left[\begin{array}{ccc}&1&\\&&\\&2&\end{array}\right]$ , determine o valor de x + y:

a) n.d.a
b) 6
c) 7
d) 8

Answer 1

3x-y = 4
  x+y=8
--------------------
4x=12
x=12/4
x=3

Substituindo x=3 em : 

x+y=8
3+y=8
y=8-3
y=5

Logo,   x+y= 5+3 =8