Question

PUC-MG: Considere as matrizes de elementos reais

A= $\left[\begin{array}{ccc}1&x\\y&z\end{array}\right]$, B=$\left[\begin{array}{ccc}1&1\\1&2\end{array}\right]$ e C=$\left[\begin{array}{ccc}3&5\\9&14\end{array}\right]$.
Sabendo que A.B=C, pode-se afirmar que a soma dos elementos de A é:
A)10; B)11; C)12; D)13

divirtam-se.

Answer 1

Ola Dudu

A.B = | x + 1  2x + 1 | |3   5|
          | y + z  y + 2z | |9 14|

x + 1 = 3
2x + 1 = 5
x = 2

y + z = 9
y + 2z = 14
z = 5
y = 4 

1 + x + y + z = 1 + 2 + 4 + 5 = 12 (C)

Answer 2

Resposta Correta:

C) 12