Linear Algebra Examples

$[\begin{array}{c} 1 + i & \frac{1}{5} & i + 7 \\ \frac{1}{2} + \frac{\sqrt{3}}{2} \cdot i & - i & 2 + 2 i \end{array}] \cdot [\begin{array}{c} e^{i \cdot \frac{π}{4}} & - 1 \\ - 2 i & 5 + 5 i \\ i & 3 \end{array}]$

Step 1

Combine $\frac{\sqrt{3}}{2}$ and $i$ .

$[\begin{array}{c} 1 + i & \frac{1}{5} & i + 7 \\ \frac{1}{2} + \frac{\sqrt{3} i}{2} & - i & 2 + 2 i \end{array}] \cdot [\begin{array}{c} e^{\frac{i π}{4}} & - 1 \\ - 2 i & 5 + 5 i \\ i & 3 \end{array}]$

Step 2

Multiply $[\begin{array}{c} 1 + i & \frac{1}{5} & i + 7 \\ \frac{1}{2} + \frac{\sqrt{3} i}{2} & - i & 2 + 2 i \end{array}] [\begin{array}{c} e^{\frac{i π}{4}} & - 1 \\ - 2 i & 5 + 5 i \\ i & 3 \end{array}]$ .

Tap for more steps...

Step 2.1

Two matrices can be multiplied if and only if the number of columns in the first matrix is equal to the number of rows in the second matrix. In this case, the first matrix is $2 \times 3$ and the second matrix is $3 \times 2$ .

Step 2.2

Multiply each row in the first matrix by each column in the second matrix.

$[\begin{array}{c} (1 + i) e^{\frac{i π}{4}} + \frac{1}{5} (- 2 i) + (i + 7) i & (1 + i) \cdot - 1 + \frac{1}{5} (5 + 5 i) + (i + 7) \cdot 3 \\ (\frac{1}{2} + \frac{\sqrt{3} i}{2}) e^{\frac{i π}{4}} - i (- 2 i) + (2 + 2 i) i & (\frac{1}{2} + \frac{\sqrt{3} i}{2}) \cdot - 1 - i (5 + 5 i) + (2 + 2 i) \cdot 3 \end{array}]$

Step 2.3

Simplify each element of the matrix by multiplying out all the expressions.

$[\begin{array}{c} - 1 + e^{\frac{π i}{4}} + e^{\frac{π i}{4}} i + \frac{33 i}{5} & 21 + 3 i \\ - 4 + \frac{e^{\frac{π i}{4}}}{2} + \frac{\sqrt{3} i e^{\frac{π i}{4}}}{2} + 2 i & \frac{21}{2} - \frac{\sqrt{3} i}{2} + i \end{array}]$

Step 3

Reorder the factors of $e^{\frac{π i}{4}} i$ .

$[\begin{array}{c} - 1 + e^{\frac{π i}{4}} + i e^{\frac{π i}{4}} + \frac{33 i}{5} & 21 + 3 i \\ - 4 + \frac{e^{\frac{π i}{4}}}{2} + \frac{\sqrt{3} i e^{\frac{π i}{4}}}{2} + 2 i & \frac{21}{2} - \frac{\sqrt{3} i}{2} + i \end{array}]$

Step 4

Add $i e^{\frac{π i}{4}}$ and $\frac{33 i}{5}$ .

Tap for more steps...

Step 4.1

Reorder $i$ and $e^{\frac{π i}{4}}$ .

Step 4.2

To write $e^{\frac{π i}{4}} i$ as a fraction with a common denominator, multiply by $\frac{5}{5}$ .

$[\begin{array}{c} - 1 + e^{\frac{π i}{4}} + e^{\frac{π i}{4}} i \cdot \frac{5}{5} + \frac{33 i}{5} & 21 + 3 i \\ - 4 + \frac{e^{\frac{π i}{4}}}{2} + \frac{\sqrt{3} i e^{\frac{π i}{4}}}{2} + 2 i & \frac{21}{2} - \frac{\sqrt{3} i}{2} + i \end{array}]$

Step 4.3

Combine $e^{\frac{π i}{4}} i$ and $\frac{5}{5}$ .

$[\begin{array}{c} - 1 + e^{\frac{π i}{4}} + \frac{e^{\frac{π i}{4}} i \cdot 5}{5} + \frac{33 i}{5} & 21 + 3 i \\ - 4 + \frac{e^{\frac{π i}{4}}}{2} + \frac{\sqrt{3} i e^{\frac{π i}{4}}}{2} + 2 i & \frac{21}{2} - \frac{\sqrt{3} i}{2} + i \end{array}]$

Step 4.4

Combine the numerators over the common denominator.

$[\begin{array}{c} - 1 + e^{\frac{π i}{4}} + \frac{5 i e^{\frac{π i}{4}} + 33 i}{5} & 21 + 3 i \\ - 4 + \frac{e^{\frac{π i}{4}}}{2} + \frac{\sqrt{3} i e^{\frac{π i}{4}}}{2} + 2 i & \frac{21}{2} - \frac{\sqrt{3} i}{2} + i \end{array}]$

Step 5

To write $- 1$ as a fraction with a common denominator, multiply by $\frac{5}{5}$ .

$[\begin{array}{c} - 1 \cdot \frac{5}{5} + \frac{5 i e^{\frac{π i}{4}} + 33 i}{5} + e^{\frac{π i}{4}} & 21 + 3 i \\ - 4 + \frac{e^{\frac{π i}{4}}}{2} + \frac{\sqrt{3} i e^{\frac{π i}{4}}}{2} + 2 i & \frac{21}{2} - \frac{\sqrt{3} i}{2} + i \end{array}]$

Step 6

Combine $- 1$ and $\frac{5}{5}$ .

$[\begin{array}{c} \frac{- 1 \cdot 5}{5} + \frac{5 i e^{\frac{π i}{4}} + 33 i}{5} + e^{\frac{π i}{4}} & 21 + 3 i \\ - 4 + \frac{e^{\frac{π i}{4}}}{2} + \frac{\sqrt{3} i e^{\frac{π i}{4}}}{2} + 2 i & \frac{21}{2} - \frac{\sqrt{3} i}{2} + i \end{array}]$

Step 7

Combine the numerators over the common denominator.

$[\begin{array}{c} \frac{- 5 + 5 i e^{\frac{π i}{4}} + 33 i}{5} + e^{\frac{π i}{4}} & 21 + 3 i \\ - 4 + \frac{e^{\frac{π i}{4}}}{2} + \frac{\sqrt{3} i e^{\frac{π i}{4}}}{2} + 2 i & \frac{21}{2} - \frac{\sqrt{3} i}{2} + i \end{array}]$

Step 8

To write $e^{\frac{π i}{4}}$ as a fraction with a common denominator, multiply by $\frac{5}{5}$ .

$[\begin{array}{c} \frac{- 5 + 5 i e^{\frac{π i}{4}} + 33 i}{5} + e^{\frac{π i}{4}} \cdot \frac{5}{5} & 21 + 3 i \\ - 4 + \frac{e^{\frac{π i}{4}}}{2} + \frac{\sqrt{3} i e^{\frac{π i}{4}}}{2} + 2 i & \frac{21}{2} - \frac{\sqrt{3} i}{2} + i \end{array}]$

Step 9

Combine $e^{\frac{π i}{4}}$ and $\frac{5}{5}$ .

$[\begin{array}{c} \frac{- 5 + 5 i e^{\frac{π i}{4}} + 33 i}{5} + \frac{e^{\frac{π i}{4}} \cdot 5}{5} & 21 + 3 i \\ - 4 + \frac{e^{\frac{π i}{4}}}{2} + \frac{\sqrt{3} i e^{\frac{π i}{4}}}{2} + 2 i & \frac{21}{2} - \frac{\sqrt{3} i}{2} + i \end{array}]$

Step 10

Combine the numerators over the common denominator.

$[\begin{array}{c} \frac{- 5 + 5 i e^{\frac{π i}{4}} + 33 i + 5 e^{\frac{π i}{4}}}{5} & 21 + 3 i \\ - 4 + \frac{e^{\frac{π i}{4}}}{2} + \frac{\sqrt{3} i e^{\frac{π i}{4}}}{2} + 2 i & \frac{21}{2} - \frac{\sqrt{3} i}{2} + i \end{array}]$