Linear Algebra Examples

$[\begin{array}{c} 10 \\ - 15 \\ 131 \end{array}] = a [\begin{array}{c} 1 \\ - 1 \\ 8 \end{array}] + b [\begin{array}{c} 2 \\ 1 \\ 7 \end{array}] + c [\begin{array}{c} 1 \\ 3 \\ - 4 \end{array}] + d [\begin{array}{c} 3 \\ - 4 \\ 36 \end{array}]$

Step 1

Simplify.

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Step 1.1

Simplify each term.

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Step 1.1.1

Multiply $a$ by each element of the matrix.

$[\begin{array}{c} 10 \\ - 15 \\ 131 \end{array}] = [\begin{array}{c} a \cdot 1 \\ a \cdot - 1 \\ a \cdot 8 \end{array}] + b [\begin{array}{c} 2 \\ 1 \\ 7 \end{array}] + c [\begin{array}{c} 1 \\ 3 \\ - 4 \end{array}] + d [\begin{array}{c} 3 \\ - 4 \\ 36 \end{array}]$

Step 1.1.2

Simplify each element in the matrix.

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Step 1.1.2.1

Multiply $a$ by $1$ .

$[\begin{array}{c} 10 \\ - 15 \\ 131 \end{array}] = [\begin{array}{c} a \\ a \cdot - 1 \\ a \cdot 8 \end{array}] + b [\begin{array}{c} 2 \\ 1 \\ 7 \end{array}] + c [\begin{array}{c} 1 \\ 3 \\ - 4 \end{array}] + d [\begin{array}{c} 3 \\ - 4 \\ 36 \end{array}]$

Step 1.1.2.2

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

$[\begin{array}{c} 10 \\ - 15 \\ 131 \end{array}] = [\begin{array}{c} a \\ - 1 \cdot a \\ a \cdot 8 \end{array}] + b [\begin{array}{c} 2 \\ 1 \\ 7 \end{array}] + c [\begin{array}{c} 1 \\ 3 \\ - 4 \end{array}] + d [\begin{array}{c} 3 \\ - 4 \\ 36 \end{array}]$

Step 1.1.2.3

Rewrite $- 1 a$ as $- a$ .

$[\begin{array}{c} 10 \\ - 15 \\ 131 \end{array}] = [\begin{array}{c} a \\ - a \\ a \cdot 8 \end{array}] + b [\begin{array}{c} 2 \\ 1 \\ 7 \end{array}] + c [\begin{array}{c} 1 \\ 3 \\ - 4 \end{array}] + d [\begin{array}{c} 3 \\ - 4 \\ 36 \end{array}]$

Step 1.1.2.4

Move $8$ to the left of $a$ .

$[\begin{array}{c} 10 \\ - 15 \\ 131 \end{array}] = [\begin{array}{c} a \\ - a \\ 8 a \end{array}] + b [\begin{array}{c} 2 \\ 1 \\ 7 \end{array}] + c [\begin{array}{c} 1 \\ 3 \\ - 4 \end{array}] + d [\begin{array}{c} 3 \\ - 4 \\ 36 \end{array}]$

Step 1.1.3

Multiply $b$ by each element of the matrix.

$[\begin{array}{c} 10 \\ - 15 \\ 131 \end{array}] = [\begin{array}{c} a \\ - a \\ 8 a \end{array}] + [\begin{array}{c} b \cdot 2 \\ b \cdot 1 \\ b \cdot 7 \end{array}] + c [\begin{array}{c} 1 \\ 3 \\ - 4 \end{array}] + d [\begin{array}{c} 3 \\ - 4 \\ 36 \end{array}]$

Step 1.1.4

Simplify each element in the matrix.

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Step 1.1.4.1

Move $2$ to the left of $b$ .

$[\begin{array}{c} 10 \\ - 15 \\ 131 \end{array}] = [\begin{array}{c} a \\ - a \\ 8 a \end{array}] + [\begin{array}{c} 2 b \\ b \cdot 1 \\ b \cdot 7 \end{array}] + c [\begin{array}{c} 1 \\ 3 \\ - 4 \end{array}] + d [\begin{array}{c} 3 \\ - 4 \\ 36 \end{array}]$

Step 1.1.4.2

Multiply $b$ by $1$ .

$[\begin{array}{c} 10 \\ - 15 \\ 131 \end{array}] = [\begin{array}{c} a \\ - a \\ 8 a \end{array}] + [\begin{array}{c} 2 b \\ b \\ b \cdot 7 \end{array}] + c [\begin{array}{c} 1 \\ 3 \\ - 4 \end{array}] + d [\begin{array}{c} 3 \\ - 4 \\ 36 \end{array}]$

Step 1.1.4.3

Move $7$ to the left of $b$ .

$[\begin{array}{c} 10 \\ - 15 \\ 131 \end{array}] = [\begin{array}{c} a \\ - a \\ 8 a \end{array}] + [\begin{array}{c} 2 b \\ b \\ 7 b \end{array}] + c [\begin{array}{c} 1 \\ 3 \\ - 4 \end{array}] + d [\begin{array}{c} 3 \\ - 4 \\ 36 \end{array}]$

Step 1.1.5

Multiply $c$ by each element of the matrix.

$[\begin{array}{c} 10 \\ - 15 \\ 131 \end{array}] = [\begin{array}{c} a \\ - a \\ 8 a \end{array}] + [\begin{array}{c} 2 b \\ b \\ 7 b \end{array}] + [\begin{array}{c} c \cdot 1 \\ c \cdot 3 \\ c \cdot - 4 \end{array}] + d [\begin{array}{c} 3 \\ - 4 \\ 36 \end{array}]$

Step 1.1.6

Simplify each element in the matrix.

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Step 1.1.6.1

Multiply $c$ by $1$ .

$[\begin{array}{c} 10 \\ - 15 \\ 131 \end{array}] = [\begin{array}{c} a \\ - a \\ 8 a \end{array}] + [\begin{array}{c} 2 b \\ b \\ 7 b \end{array}] + [\begin{array}{c} c \\ c \cdot 3 \\ c \cdot - 4 \end{array}] + d [\begin{array}{c} 3 \\ - 4 \\ 36 \end{array}]$

Step 1.1.6.2

Move $3$ to the left of $c$ .

$[\begin{array}{c} 10 \\ - 15 \\ 131 \end{array}] = [\begin{array}{c} a \\ - a \\ 8 a \end{array}] + [\begin{array}{c} 2 b \\ b \\ 7 b \end{array}] + [\begin{array}{c} c \\ 3 c \\ c \cdot - 4 \end{array}] + d [\begin{array}{c} 3 \\ - 4 \\ 36 \end{array}]$

Step 1.1.6.3

Move $- 4$ to the left of $c$ .

$[\begin{array}{c} 10 \\ - 15 \\ 131 \end{array}] = [\begin{array}{c} a \\ - a \\ 8 a \end{array}] + [\begin{array}{c} 2 b \\ b \\ 7 b \end{array}] + [\begin{array}{c} c \\ 3 c \\ - 4 c \end{array}] + d [\begin{array}{c} 3 \\ - 4 \\ 36 \end{array}]$

Step 1.1.7

Multiply $d$ by each element of the matrix.

Step 1.1.8

Simplify each element in the matrix.

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Step 1.1.8.1

Move $3$ to the left of $d$ .

Step 1.1.8.2

Move $- 4$ to the left of $d$ .

Step 1.1.8.3

Move $36$ to the left of $d$ .

Step 1.2

Add the corresponding elements.

$[\begin{array}{c} 10 \\ - 15 \\ 131 \end{array}] = [\begin{array}{c} a + 2 b \\ - a + b \\ 8 a + 7 b \end{array}] + [\begin{array}{c} c \\ 3 c \\ - 4 c \end{array}] + [\begin{array}{c} 3 d \\ - 4 d \\ 36 d \end{array}]$

Step 1.3

Add the corresponding elements.

$[\begin{array}{c} 10 \\ - 15 \\ 131 \end{array}] = [\begin{array}{c} a + 2 b + c \\ - a + b + 3 c \\ 8 a + 7 b - 4 c \end{array}] + [\begin{array}{c} 3 d \\ - 4 d \\ 36 d \end{array}]$

Step 1.4

Add the corresponding elements.

$[\begin{array}{c} 10 \\ - 15 \\ 131 \end{array}] = [\begin{array}{c} a + 2 b + c + 3 d \\ - a + b + 3 c - 4 d \\ 8 a + 7 b - 4 c + 36 d \end{array}]$

Step 2

The matrix equation can be written as a set of equations.

$10 = a + 2 b + c + 3 d$

$- 15 = - a + b + 3 c - 4 d$

$131 = 8 a + 7 b - 4 c + 36 d$