91Ó°ÊÓ

Perform the indicated multiplications. $$\left[\begin{array}{rr} -1 & 7 \\ 3 & 5 \\ 10 & -1 \\ -5 & 12 \end{array}\right]\left[\begin{array}{rr} 2 & 1 \\ 5 & -3 \end{array}\right]$$

Solve the given systems of equations by Gaussian elimination. If there is an unlimited number of solutions, find two of them. $$\begin{aligned} &9 x-3 y+6 z=9\\\ &4 x-2 y+z=3\\\ &6 x+6 y+3 z=4 \end{aligned}$$

Perform the indicated multiplications. $$\left[\begin{array}{rr} 5 & 4 \end{array}\right]\left[\begin{array}{rr} 4 & -4 \\ -5 & 5 \end{array}\right]$$

Solve the given systems of equations by using the inverse of the coefficient matrix $$\begin{aligned} &x+2 y=3\\\ &3 x+4 y=11 \end{aligned}$$

$$\left[\begin{array}{rr} 2 & -3 \\ 8 & -1 \end{array}\right]\left[\begin{array}{rrr} 3 & 0 & -1 \\ 7 & -5 & 6 \end{array}\right]$$

Solve the given systems of equations by Gaussian elimination. If there is an unlimited number of solutions, find two of them. $$\begin{aligned} &w+2 x-y+3 z=12\\\ &2 w-2 y-z=3\\\ &3 x-y-z=-1\\\ &-w+2 x+y+2 z=3 \end{aligned}$$

Solve the given systems of equations by using the inverse of the coefficient matrix $$\begin{aligned} &2.5 x+2.8 y=-3.0\\\ &3.5 x-1.6 y=9.6 \end{aligned}$$

Evaluate the given determinants by expansion by minors. $$\left|\begin{array}{rrr} 2 & 0 & 0 \\ -2 & 1 & 4 \\ 4 & -2 & 3 \end{array}\right|$$

Find the indicated sums of matrices. $$\left[\begin{array}{rr}6 & 3 \\ -5 & -4\end{array}\right]+\left[\begin{array}{rr}-1 & 7 \\ 5 & -2\end{array}\right]$$

Use a graphing calculator to perform the indicate multiplications. $$\left[\begin{array}{rr} -7 & 8 \\ 5 & 0 \end{array}\right]\left[\begin{array}{rr} -90 & 100 \\ 10 & 40 \end{array}\right]$$