Question

Me ajudem por favor ​

Answer 1

Explicação passo-a-passo:

$\sf A\cdot B=C$

$\sf \left[\begin{array}{cc} \sf x & \sf 0 \\ \sf 2 & \sf 1 \end{array}\right]\cdot\left[\begin{array}{cc} \sf 2 & \sf 1 \\ \sf y & \sf 0 \end{array}\right]=\left[\begin{array}{cc} \sf 2 & \sf 1 \\ \sf 3 & \sf z \end{array}\right]$

$\sf \left[\begin{array}{cc} \sf x\cdot2+0\cdot y & \sf x\cdot1+0\cdot0 \\ \sf 2\cdot2+1\cdot y & \sf 2\cdot1+1\cdot0 \end{array}\right]=\left[\begin{array}{cc} \sf 2 & \sf 1 \\ \sf 3 & \sf z \end{array}\right]$

$\sf \left[\begin{array}{cc} \sf 2x+0 & \sf x+0 \\ \sf 4+y & \sf 2+0 \end{array}\right]=\left[\begin{array}{cc} \sf 2 & \sf 1 \\ \sf 3 & \sf z \end{array}\right]$

$\sf \left[\begin{array}{cc} \sf 2x & \sf x \\ \sf y+4 & \sf 2 \end{array}\right]=\left[\begin{array}{cc} \sf 2 & \sf 1 \\ \sf 3 & \sf z \end{array}\right]$

Assim:

• $\sf \red{x=1}$

• $\sf y+4=3~\Rightarrow~y=3-4~\Rightarrow~\red{y=-1}$

• $\sf \red{z=2}$

a) Falso, $\sf x\ne y$

b) Falso, $\sf z=-2y$

c) Verdadeiro, $\sf 1\cdot(-1)=-1$

d) Falso, $\sf y+z=-1+2~\Rightarrow~y+z=1$

Letra C