Linear Algebra Examples

$[\begin{array}{c} 2 & 2 \\ - 1 + 3 i & - 1 - 3 i \end{array}]$

Step 1

The inverse of a $2 \times 2$ matrix can be found using the formula $\frac{1}{a d - b c} [\begin{array}{c} d & - b \\ - c & a \end{array}]$ where $a d - b c$ is the determinant.

Step 2

Find the determinant.

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Step 2.1

The determinant of a $2 \times 2$ matrix can be found using the formula $| \begin{array}{c} a & b \\ c & d \end{array} | = a d - c b$ .

$2 (- 1 - 3 i) - (- 1 + 3 i) \cdot 2$

Step 2.2

Simplify the determinant.

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Step 2.2.1

Simplify each term.

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Step 2.2.1.1

Apply the distributive property.

$2 \cdot - 1 + 2 (- 3 i) - (- 1 + 3 i) \cdot 2$

Step 2.2.1.2

Multiply $2$ by $- 1$ .

$- 2 + 2 (- 3 i) - (- 1 + 3 i) \cdot 2$

Step 2.2.1.3

Multiply $- 3$ by $2$ .

$- 2 - 6 i - (- 1 + 3 i) \cdot 2$

Step 2.2.1.4

Apply the distributive property.

$- 2 - 6 i + (- - 1 - (3 i)) \cdot 2$

Step 2.2.1.5

Multiply $- 1$ by $- 1$ .

$- 2 - 6 i + (1 - (3 i)) \cdot 2$

Step 2.2.1.6

Multiply $3$ by $- 1$ .

$- 2 - 6 i + (1 - 3 i) \cdot 2$

Step 2.2.1.7

Apply the distributive property.

$- 2 - 6 i + 1 \cdot 2 - 3 i \cdot 2$

Step 2.2.1.8

Multiply $2$ by $1$ .

$- 2 - 6 i + 2 - 3 i \cdot 2$

Step 2.2.1.9

Multiply $2$ by $- 3$ .

$- 2 - 6 i + 2 - 6 i$

Step 2.2.2

Add $- 2$ and $2$ .

$0 - 6 i - 6 i$

Step 2.2.3

Subtract $6 i$ from $0$ .

$- 6 i - 6 i$

Step 2.2.4

Subtract $6 i$ from $- 6 i$ .

$- 12 i$

Step 3

Since the determinant is non-zero, the inverse exists.

Step 4

Substitute the known values into the formula for the inverse.

$\frac{1}{- 12 i} [\begin{array}{c} - 1 - 3 i & - 2 \\ - (- 1 + 3 i) & 2 \end{array}]$

Step 5

Multiply the numerator and denominator of $\frac{1}{- 12 i}$ by the conjugate of $- 12 i$ to make the denominator real.

$\frac{1}{- 12 i} \cdot \frac{i}{i} [\begin{array}{c} - 1 - 3 i & - 2 \\ - (- 1 + 3 i) & 2 \end{array}]$

Step 6

Multiply.

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Step 6.1

Combine.

$\frac{1 i}{- 12 i i} [\begin{array}{c} - 1 - 3 i & - 2 \\ - (- 1 + 3 i) & 2 \end{array}]$

Step 6.2

Multiply $i$ by $1$ .

$\frac{i}{- 12 i i} [\begin{array}{c} - 1 - 3 i & - 2 \\ - (- 1 + 3 i) & 2 \end{array}]$

Step 6.3

Simplify the denominator.

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Step 6.3.1

Add parentheses.

$\frac{i}{- 12 (i i)} [\begin{array}{c} - 1 - 3 i & - 2 \\ - (- 1 + 3 i) & 2 \end{array}]$

Step 6.3.2

Raise $i$ to the power of $1$ .

$\frac{i}{- 12 (i^{1} i)} [\begin{array}{c} - 1 - 3 i & - 2 \\ - (- 1 + 3 i) & 2 \end{array}]$

Step 6.3.3

Raise $i$ to the power of $1$ .

$\frac{i}{- 12 (i^{1} i^{1})} [\begin{array}{c} - 1 - 3 i & - 2 \\ - (- 1 + 3 i) & 2 \end{array}]$

Step 6.3.4

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$\frac{i}{- 12 i^{1 + 1}} [\begin{array}{c} - 1 - 3 i & - 2 \\ - (- 1 + 3 i) & 2 \end{array}]$

Step 6.3.5

Add $1$ and $1$ .

$\frac{i}{- 12 i^{2}} [\begin{array}{c} - 1 - 3 i & - 2 \\ - (- 1 + 3 i) & 2 \end{array}]$

Step 6.3.6

Rewrite $i^{2}$ as $- 1$ .

$\frac{i}{- 12 \cdot - 1} [\begin{array}{c} - 1 - 3 i & - 2 \\ - (- 1 + 3 i) & 2 \end{array}]$

Step 7

Multiply $- 12$ by $- 1$ .

$\frac{i}{12} [\begin{array}{c} - 1 - 3 i & - 2 \\ - (- 1 + 3 i) & 2 \end{array}]$

Step 8

Apply the distributive property.

$\frac{i}{12} [\begin{array}{c} - 1 - 3 i & - 2 \\ - - 1 - (3 i) & 2 \end{array}]$

Step 9

Multiply $- 1$ by $- 1$ .

$\frac{i}{12} [\begin{array}{c} - 1 - 3 i & - 2 \\ 1 - (3 i) & 2 \end{array}]$

Step 10

Multiply $3$ by $- 1$ .

$\frac{i}{12} [\begin{array}{c} - 1 - 3 i & - 2 \\ 1 - 3 i & 2 \end{array}]$

Step 11

Multiply $\frac{i}{12}$ by each element of the matrix.

$[\begin{array}{c} \frac{i}{12} (- 1 - 3 i) & \frac{i}{12} \cdot - 2 \\ \frac{i}{12} (1 - 3 i) & \frac{i}{12} \cdot 2 \end{array}]$

Step 12

Simplify each element in the matrix.

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Step 12.1

Apply the distributive property.

$[\begin{array}{c} \frac{i}{12} \cdot - 1 + \frac{i}{12} (- 3 i) & \frac{i}{12} \cdot - 2 \\ \frac{i}{12} (1 - 3 i) & \frac{i}{12} \cdot 2 \end{array}]$

Step 12.2

Combine $\frac{i}{12}$ and $- 1$ .

$[\begin{array}{c} \frac{i \cdot - 1}{12} + \frac{i}{12} (- 3 i) & \frac{i}{12} \cdot - 2 \\ \frac{i}{12} (1 - 3 i) & \frac{i}{12} \cdot 2 \end{array}]$

Step 12.3

Cancel the common factor of $3$ .

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Step 12.3.1

Factor $3$ out of $12$ .

$[\begin{array}{c} \frac{i \cdot - 1}{12} + \frac{i}{3 (4)} (- 3 i) & \frac{i}{12} \cdot - 2 \\ \frac{i}{12} (1 - 3 i) & \frac{i}{12} \cdot 2 \end{array}]$

Step 12.3.2

Factor $3$ out of $- 3 i$ .

$[\begin{array}{c} \frac{i \cdot - 1}{12} + \frac{i}{3 (4)} (3 (- i)) & \frac{i}{12} \cdot - 2 \\ \frac{i}{12} (1 - 3 i) & \frac{i}{12} \cdot 2 \end{array}]$

Step 12.3.3

Cancel the common factor.

$[\begin{array}{c} \frac{i \cdot - 1}{12} + \frac{i}{3 \cdot 4} (3 (- i)) & \frac{i}{12} \cdot - 2 \\ \frac{i}{12} (1 - 3 i) & \frac{i}{12} \cdot 2 \end{array}]$

Step 12.3.4

Rewrite the expression.

$[\begin{array}{c} \frac{i \cdot - 1}{12} + \frac{i}{4} (- i) & \frac{i}{12} \cdot - 2 \\ \frac{i}{12} (1 - 3 i) & \frac{i}{12} \cdot 2 \end{array}]$

Step 12.4

Combine $\frac{i}{4}$ and $i$ .

$[\begin{array}{c} \frac{i \cdot - 1}{12} - \frac{i i}{4} & \frac{i}{12} \cdot - 2 \\ \frac{i}{12} (1 - 3 i) & \frac{i}{12} \cdot 2 \end{array}]$

Step 12.5

Raise $i$ to the power of $1$ .

$[\begin{array}{c} \frac{i \cdot - 1}{12} - \frac{i^{1} i}{4} & \frac{i}{12} \cdot - 2 \\ \frac{i}{12} (1 - 3 i) & \frac{i}{12} \cdot 2 \end{array}]$

Step 12.6

Raise $i$ to the power of $1$ .

$[\begin{array}{c} \frac{i \cdot - 1}{12} - \frac{i^{1} i^{1}}{4} & \frac{i}{12} \cdot - 2 \\ \frac{i}{12} (1 - 3 i) & \frac{i}{12} \cdot 2 \end{array}]$

Step 12.7

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$[\begin{array}{c} \frac{i \cdot - 1}{12} - \frac{i^{1 + 1}}{4} & \frac{i}{12} \cdot - 2 \\ \frac{i}{12} (1 - 3 i) & \frac{i}{12} \cdot 2 \end{array}]$

Step 12.8

Add $1$ and $1$ .

$[\begin{array}{c} \frac{i \cdot - 1}{12} - \frac{i^{2}}{4} & \frac{i}{12} \cdot - 2 \\ \frac{i}{12} (1 - 3 i) & \frac{i}{12} \cdot 2 \end{array}]$

Step 12.9

Simplify each term.

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Step 12.9.1

Simplify the numerator.

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Step 12.9.1.1

Move $- 1$ to the left of $i$ .

$[\begin{array}{c} \frac{- 1 \cdot i}{12} - \frac{i^{2}}{4} & \frac{i}{12} \cdot - 2 \\ \frac{i}{12} (1 - 3 i) & \frac{i}{12} \cdot 2 \end{array}]$

Step 12.9.1.2

Rewrite $- 1 i$ as $- i$ .

$[\begin{array}{c} \frac{- i}{12} - \frac{i^{2}}{4} & \frac{i}{12} \cdot - 2 \\ \frac{i}{12} (1 - 3 i) & \frac{i}{12} \cdot 2 \end{array}]$

Step 12.9.2

Move the negative in front of the fraction.

$[\begin{array}{c} - \frac{i}{12} - \frac{i^{2}}{4} & \frac{i}{12} \cdot - 2 \\ \frac{i}{12} (1 - 3 i) & \frac{i}{12} \cdot 2 \end{array}]$

Step 12.9.3

Rewrite $i^{2}$ as $- 1$ .

$[\begin{array}{c} - \frac{i}{12} - \frac{- 1}{4} & \frac{i}{12} \cdot - 2 \\ \frac{i}{12} (1 - 3 i) & \frac{i}{12} \cdot 2 \end{array}]$

Step 12.9.4

Move the negative in front of the fraction.

$[\begin{array}{c} - \frac{i}{12} - - \frac{1}{4} & \frac{i}{12} \cdot - 2 \\ \frac{i}{12} (1 - 3 i) & \frac{i}{12} \cdot 2 \end{array}]$

Step 12.9.5

Multiply $- - \frac{1}{4}$ .

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Step 12.9.5.1

Multiply $- 1$ by $- 1$ .

$[\begin{array}{c} - \frac{i}{12} + 1 (\frac{1}{4}) & \frac{i}{12} \cdot - 2 \\ \frac{i}{12} (1 - 3 i) & \frac{i}{12} \cdot 2 \end{array}]$

Step 12.9.5.2

Multiply $\frac{1}{4}$ by $1$ .

$[\begin{array}{c} - \frac{i}{12} + \frac{1}{4} & \frac{i}{12} \cdot - 2 \\ \frac{i}{12} (1 - 3 i) & \frac{i}{12} \cdot 2 \end{array}]$

Step 12.10

Reorder $- \frac{i}{12}$ and $\frac{1}{4}$ .

$[\begin{array}{c} \frac{1}{4} - \frac{i}{12} & \frac{i}{12} \cdot - 2 \\ \frac{i}{12} (1 - 3 i) & \frac{i}{12} \cdot 2 \end{array}]$

Step 12.11

Cancel the common factor of $2$ .

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Step 12.11.1

Factor $2$ out of $12$ .

$[\begin{array}{c} \frac{1}{4} - \frac{i}{12} & \frac{i}{2 (6)} \cdot - 2 \\ \frac{i}{12} (1 - 3 i) & \frac{i}{12} \cdot 2 \end{array}]$

Step 12.11.2

Factor $2$ out of $- 2$ .

$[\begin{array}{c} \frac{1}{4} - \frac{i}{12} & \frac{i}{2 \cdot 6} \cdot (2 \cdot - 1) \\ \frac{i}{12} (1 - 3 i) & \frac{i}{12} \cdot 2 \end{array}]$

Step 12.11.3

Cancel the common factor.

$[\begin{array}{c} \frac{1}{4} - \frac{i}{12} & \frac{i}{2 \cdot 6} \cdot (2 \cdot - 1) \\ \frac{i}{12} (1 - 3 i) & \frac{i}{12} \cdot 2 \end{array}]$

Step 12.11.4

Rewrite the expression.

$[\begin{array}{c} \frac{1}{4} - \frac{i}{12} & \frac{i}{6} \cdot - 1 \\ \frac{i}{12} (1 - 3 i) & \frac{i}{12} \cdot 2 \end{array}]$

Step 12.12

Combine $\frac{i}{6}$ and $- 1$ .

$[\begin{array}{c} \frac{1}{4} - \frac{i}{12} & \frac{i \cdot - 1}{6} \\ \frac{i}{12} (1 - 3 i) & \frac{i}{12} \cdot 2 \end{array}]$

Step 12.13

Simplify the numerator.

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Step 12.13.1

Move $- 1$ to the left of $i$ .

$[\begin{array}{c} \frac{1}{4} - \frac{i}{12} & \frac{- 1 \cdot i}{6} \\ \frac{i}{12} (1 - 3 i) & \frac{i}{12} \cdot 2 \end{array}]$

Step 12.13.2

Rewrite $- 1 i$ as $- i$ .

$[\begin{array}{c} \frac{1}{4} - \frac{i}{12} & \frac{- i}{6} \\ \frac{i}{12} (1 - 3 i) & \frac{i}{12} \cdot 2 \end{array}]$

Step 12.14

Move the negative in front of the fraction.

$[\begin{array}{c} \frac{1}{4} - \frac{i}{12} & - \frac{i}{6} \\ \frac{i}{12} (1 - 3 i) & \frac{i}{12} \cdot 2 \end{array}]$

Step 12.15

Apply the distributive property.

$[\begin{array}{c} \frac{1}{4} - \frac{i}{12} & - \frac{i}{6} \\ \frac{i}{12} \cdot 1 + \frac{i}{12} (- 3 i) & \frac{i}{12} \cdot 2 \end{array}]$

Step 12.16

Multiply $\frac{i}{12}$ by $1$ .

$[\begin{array}{c} \frac{1}{4} - \frac{i}{12} & - \frac{i}{6} \\ \frac{i}{12} + \frac{i}{12} (- 3 i) & \frac{i}{12} \cdot 2 \end{array}]$

Step 12.17

Cancel the common factor of $3$ .

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Step 12.17.1

Factor $3$ out of $12$ .

$[\begin{array}{c} \frac{1}{4} - \frac{i}{12} & - \frac{i}{6} \\ \frac{i}{12} + \frac{i}{3 (4)} (- 3 i) & \frac{i}{12} \cdot 2 \end{array}]$

Step 12.17.2

Factor $3$ out of $- 3 i$ .

$[\begin{array}{c} \frac{1}{4} - \frac{i}{12} & - \frac{i}{6} \\ \frac{i}{12} + \frac{i}{3 (4)} (3 (- i)) & \frac{i}{12} \cdot 2 \end{array}]$

Step 12.17.3

Cancel the common factor.

$[\begin{array}{c} \frac{1}{4} - \frac{i}{12} & - \frac{i}{6} \\ \frac{i}{12} + \frac{i}{3 \cdot 4} (3 (- i)) & \frac{i}{12} \cdot 2 \end{array}]$

Step 12.17.4

Rewrite the expression.

$[\begin{array}{c} \frac{1}{4} - \frac{i}{12} & - \frac{i}{6} \\ \frac{i}{12} + \frac{i}{4} (- i) & \frac{i}{12} \cdot 2 \end{array}]$

Step 12.18

Combine $\frac{i}{4}$ and $i$ .

$[\begin{array}{c} \frac{1}{4} - \frac{i}{12} & - \frac{i}{6} \\ \frac{i}{12} - \frac{i i}{4} & \frac{i}{12} \cdot 2 \end{array}]$

Step 12.19

Raise $i$ to the power of $1$ .

$[\begin{array}{c} \frac{1}{4} - \frac{i}{12} & - \frac{i}{6} \\ \frac{i}{12} - \frac{i^{1} i}{4} & \frac{i}{12} \cdot 2 \end{array}]$

Step 12.20

Raise $i$ to the power of $1$ .

$[\begin{array}{c} \frac{1}{4} - \frac{i}{12} & - \frac{i}{6} \\ \frac{i}{12} - \frac{i^{1} i^{1}}{4} & \frac{i}{12} \cdot 2 \end{array}]$

Step 12.21

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$[\begin{array}{c} \frac{1}{4} - \frac{i}{12} & - \frac{i}{6} \\ \frac{i}{12} - \frac{i^{1 + 1}}{4} & \frac{i}{12} \cdot 2 \end{array}]$

Step 12.22

Add $1$ and $1$ .

$[\begin{array}{c} \frac{1}{4} - \frac{i}{12} & - \frac{i}{6} \\ \frac{i}{12} - \frac{i^{2}}{4} & \frac{i}{12} \cdot 2 \end{array}]$

Step 12.23

Simplify each term.

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Step 12.23.1

Rewrite $i^{2}$ as $- 1$ .

$[\begin{array}{c} \frac{1}{4} - \frac{i}{12} & - \frac{i}{6} \\ \frac{i}{12} - \frac{- 1}{4} & \frac{i}{12} \cdot 2 \end{array}]$

Step 12.23.2

Move the negative in front of the fraction.

$[\begin{array}{c} \frac{1}{4} - \frac{i}{12} & - \frac{i}{6} \\ \frac{i}{12} - - \frac{1}{4} & \frac{i}{12} \cdot 2 \end{array}]$

Step 12.23.3

Multiply $- - \frac{1}{4}$ .

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Step 12.23.3.1

Multiply $- 1$ by $- 1$ .

$[\begin{array}{c} \frac{1}{4} - \frac{i}{12} & - \frac{i}{6} \\ \frac{i}{12} + 1 (\frac{1}{4}) & \frac{i}{12} \cdot 2 \end{array}]$

Step 12.23.3.2

Multiply $\frac{1}{4}$ by $1$ .

$[\begin{array}{c} \frac{1}{4} - \frac{i}{12} & - \frac{i}{6} \\ \frac{i}{12} + \frac{1}{4} & \frac{i}{12} \cdot 2 \end{array}]$

Step 12.24

Reorder $\frac{i}{12}$ and $\frac{1}{4}$ .

$[\begin{array}{c} \frac{1}{4} - \frac{i}{12} & - \frac{i}{6} \\ \frac{1}{4} + \frac{i}{12} & \frac{i}{12} \cdot 2 \end{array}]$

Step 12.25

Cancel the common factor of $2$ .

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Step 12.25.1

Factor $2$ out of $12$ .

$[\begin{array}{c} \frac{1}{4} - \frac{i}{12} & - \frac{i}{6} \\ \frac{1}{4} + \frac{i}{12} & \frac{i}{2 (6)} \cdot 2 \end{array}]$

Step 12.25.2

Cancel the common factor.

$[\begin{array}{c} \frac{1}{4} - \frac{i}{12} & - \frac{i}{6} \\ \frac{1}{4} + \frac{i}{12} & \frac{i}{2 \cdot 6} \cdot 2 \end{array}]$

Step 12.25.3

Rewrite the expression.

$[\begin{array}{c} \frac{1}{4} - \frac{i}{12} & - \frac{i}{6} \\ \frac{1}{4} + \frac{i}{12} & \frac{i}{6} \end{array}]$