Precalculus Examples

$v = - 7 i - 2 j$ , $w = 5 i + 4 j$

Step 1

Solve the equation for $i$ .

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Step 1.1

Rewrite the equation as $- 7 i - 2 j = v$ .

$- 7 i - 2 j = v$

$w = 5 i + 4 j$

Step 1.2

Add $2 j$ to both sides of the equation.

$- 7 i = v + 2 j$

$w = 5 i + 4 j$

Step 1.3

Divide each term in $- 7 i = v + 2 j$ by $- 7$ and simplify.

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Step 1.3.1

Divide each term in $- 7 i = v + 2 j$ by $- 7$ .

$\frac{- 7 i}{- 7} = \frac{v}{- 7} + \frac{2 j}{- 7}$

$w = 5 i + 4 j$

Step 1.3.2

Simplify the left side.

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Step 1.3.2.1

Cancel the common factor of $- 7$ .

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Step 1.3.2.1.1

Cancel the common factor.

$\frac{- 7 i}{- 7} = \frac{v}{- 7} + \frac{2 j}{- 7}$

$w = 5 i + 4 j$

Step 1.3.2.1.2

Divide $i$ by $1$ .

$i = \frac{v}{- 7} + \frac{2 j}{- 7}$

$w = 5 i + 4 j$

$i = \frac{v}{- 7} + \frac{2 j}{- 7}$

$w = 5 i + 4 j$

$i = \frac{v}{- 7} + \frac{2 j}{- 7}$

$w = 5 i + 4 j$

Step 1.3.3

Simplify the right side.

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Step 1.3.3.1

Simplify each term.

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Step 1.3.3.1.1

Move the negative in front of the fraction.

$i = - \frac{v}{7} + \frac{2 j}{- 7}$

$w = 5 i + 4 j$

Step 1.3.3.1.2

Move the negative in front of the fraction.

$i = - \frac{v}{7} - \frac{2 j}{7}$

$w = 5 i + 4 j$

$i = - \frac{v}{7} - \frac{2 j}{7}$

$w = 5 i + 4 j$

$i = - \frac{v}{7} - \frac{2 j}{7}$

$w = 5 i + 4 j$

$i = - \frac{v}{7} - \frac{2 j}{7}$

$w = 5 i + 4 j$

$i = - \frac{v}{7} - \frac{2 j}{7}$

$w = 5 i + 4 j$

Step 2

Simplify $5 (- \frac{v}{7} - \frac{2 j}{7}) + 4 j$ .

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Step 2.1

Simplify each term.

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Step 2.1.1

Apply the distributive property.

$w = 5 (- \frac{v}{7}) + 5 (- \frac{2 j}{7}) + 4 j$

$i = - \frac{v}{7} - \frac{2 j}{7}$

Step 2.1.2

Multiply $5 (- \frac{v}{7})$ .

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Step 2.1.2.1

Multiply $- 1$ by $5$ .

$w = - 5 \frac{v}{7} + 5 (- \frac{2 j}{7}) + 4 j$

$i = - \frac{v}{7} - \frac{2 j}{7}$

Step 2.1.2.2

Combine $- 5$ and $\frac{v}{7}$ .

$w = \frac{- 5 v}{7} + 5 (- \frac{2 j}{7}) + 4 j$

$i = - \frac{v}{7} - \frac{2 j}{7}$

$w = \frac{- 5 v}{7} + 5 (- \frac{2 j}{7}) + 4 j$

$i = - \frac{v}{7} - \frac{2 j}{7}$

Step 2.1.3

Multiply $5 (- \frac{2 j}{7})$ .

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Step 2.1.3.1

Multiply $- 1$ by $5$ .

$w = \frac{- 5 v}{7} - 5 \frac{2 j}{7} + 4 j$

$i = - \frac{v}{7} - \frac{2 j}{7}$

Step 2.1.3.2

Combine $- 5$ and $\frac{2 j}{7}$ .

$w = \frac{- 5 v}{7} + \frac{- 5 (2 j)}{7} + 4 j$

$i = - \frac{v}{7} - \frac{2 j}{7}$

Step 2.1.3.3

Multiply $2$ by $- 5$ .

$w = \frac{- 5 v}{7} + \frac{- 10 j}{7} + 4 j$

$i = - \frac{v}{7} - \frac{2 j}{7}$

$w = \frac{- 5 v}{7} + \frac{- 10 j}{7} + 4 j$

$i = - \frac{v}{7} - \frac{2 j}{7}$

Step 2.1.4

Simplify each term.

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Step 2.1.4.1

Move the negative in front of the fraction.

$w = - \frac{5 v}{7} + \frac{- 10 j}{7} + 4 j$

$i = - \frac{v}{7} - \frac{2 j}{7}$

Step 2.1.4.2

Move the negative in front of the fraction.

$w = - \frac{5 v}{7} - \frac{10 j}{7} + 4 j$

$i = - \frac{v}{7} - \frac{2 j}{7}$

$w = - \frac{5 v}{7} - \frac{10 j}{7} + 4 j$

$i = - \frac{v}{7} - \frac{2 j}{7}$

$w = - \frac{5 v}{7} - \frac{10 j}{7} + 4 j$

$i = - \frac{v}{7} - \frac{2 j}{7}$

Step 2.2

To write $4 j$ as a fraction with a common denominator, multiply by $\frac{7}{7}$ .

$w = - \frac{5 v}{7} - \frac{10 j}{7} + 4 j \cdot \frac{7}{7}$

$i = - \frac{v}{7} - \frac{2 j}{7}$

Step 2.3

Combine $4 j$ and $\frac{7}{7}$ .

$w = - \frac{5 v}{7} - \frac{10 j}{7} + \frac{4 j \cdot 7}{7}$

$i = - \frac{v}{7} - \frac{2 j}{7}$

Step 2.4

Combine the numerators over the common denominator.

$w = - \frac{5 v}{7} + \frac{- 10 j + 4 j \cdot 7}{7}$

$i = - \frac{v}{7} - \frac{2 j}{7}$

Step 2.5

Combine the numerators over the common denominator.

$w = \frac{- 5 v - 10 j + 4 j \cdot 7}{7}$

$i = - \frac{v}{7} - \frac{2 j}{7}$

Step 2.6

Multiply $7$ by $4$ .

$w = \frac{- 5 v - 10 j + 28 j}{7}$

$i = - \frac{v}{7} - \frac{2 j}{7}$

Step 2.7

Add $- 10 j$ and $28 j$ .

$w = \frac{- 5 v + 18 j}{7}$

$i = - \frac{v}{7} - \frac{2 j}{7}$

Step 2.8

Reorder $- 5 v$ and $18 j$ .

$w = \frac{18 j - 5 v}{7}$

$i = - \frac{v}{7} - \frac{2 j}{7}$

$w = \frac{18 j - 5 v}{7}$

$i = - \frac{v}{7} - \frac{2 j}{7}$

Step 3

Solve the equation for $j$ .

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Step 3.1

Rewrite the equation as $- 7 (- \frac{v}{7} - \frac{2 j}{7}) - 2 j = v$ .

$- 7 (- \frac{v}{7} - \frac{2 j}{7}) - 2 j = v$

$i = - \frac{v}{7} - \frac{2 j}{7}$

Step 3.2

Simplify $- 7 (- \frac{v}{7} - \frac{2 j}{7}) - 2 j$ .

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Step 3.2.1

Simplify each term.

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Step 3.2.1.1

Apply the distributive property.

$- 7 (- \frac{v}{7}) - 7 (- \frac{2 j}{7}) - 2 j = v$

$i = - \frac{v}{7} - \frac{2 j}{7}$

Step 3.2.1.2

Cancel the common factor of $7$ .

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Step 3.2.1.2.1

Move the leading negative in $- \frac{v}{7}$ into the numerator.

$- 7 \frac{- v}{7} - 7 (- \frac{2 j}{7}) - 2 j = v$

$i = - \frac{v}{7} - \frac{2 j}{7}$

Step 3.2.1.2.2

Factor $7$ out of $- 7$ .

$7 (- 1) (\frac{- v}{7}) - 7 (- \frac{2 j}{7}) - 2 j = v$

$i = - \frac{v}{7} - \frac{2 j}{7}$

Step 3.2.1.2.3

Cancel the common factor.

$7 \cdot (- 1 \frac{- v}{7}) - 7 (- \frac{2 j}{7}) - 2 j = v$

$i = - \frac{v}{7} - \frac{2 j}{7}$

Step 3.2.1.2.4

Rewrite the expression.

$- 1 (- v) - 7 (- \frac{2 j}{7}) - 2 j = v$

$i = - \frac{v}{7} - \frac{2 j}{7}$

$- 1 (- v) - 7 (- \frac{2 j}{7}) - 2 j = v$

$i = - \frac{v}{7} - \frac{2 j}{7}$

Step 3.2.1.3

Multiply $- 1$ by $- 1$ .

$1 v - 7 (- \frac{2 j}{7}) - 2 j = v$

$i = - \frac{v}{7} - \frac{2 j}{7}$

Step 3.2.1.4

Multiply $v$ by $1$ .

$v - 7 (- \frac{2 j}{7}) - 2 j = v$

$i = - \frac{v}{7} - \frac{2 j}{7}$

Step 3.2.1.5

Cancel the common factor of $7$ .

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Step 3.2.1.5.1

Move the leading negative in $- \frac{2 j}{7}$ into the numerator.

$v - 7 \frac{- 2 j}{7} - 2 j = v$

$i = - \frac{v}{7} - \frac{2 j}{7}$

Step 3.2.1.5.2

Factor $7$ out of $- 7$ .

$v + 7 (- 1) (\frac{- 2 j}{7}) - 2 j = v$

$i = - \frac{v}{7} - \frac{2 j}{7}$

Step 3.2.1.5.3

Cancel the common factor.

$v + 7 \cdot (- 1 \frac{- 2 j}{7}) - 2 j = v$

$i = - \frac{v}{7} - \frac{2 j}{7}$

Step 3.2.1.5.4

Rewrite the expression.

$v - 1 (- 2 j) - 2 j = v$

$i = - \frac{v}{7} - \frac{2 j}{7}$

$v - 1 (- 2 j) - 2 j = v$

$i = - \frac{v}{7} - \frac{2 j}{7}$

Step 3.2.1.6

Multiply $- 2$ by $- 1$ .

$v + 2 j - 2 j = v$

$i = - \frac{v}{7} - \frac{2 j}{7}$

$v + 2 j - 2 j = v$

$i = - \frac{v}{7} - \frac{2 j}{7}$

Step 3.2.2

Combine the opposite terms in $v + 2 j - 2 j$ .

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Step 3.2.2.1

Subtract $2 j$ from $2 j$ .

$v + 0 = v$

$i = - \frac{v}{7} - \frac{2 j}{7}$

Step 3.2.2.2

Add $v$ and $0$ .

$v = v$

$i = - \frac{v}{7} - \frac{2 j}{7}$

$v = v$

$i = - \frac{v}{7} - \frac{2 j}{7}$

$v = v$

$i = - \frac{v}{7} - \frac{2 j}{7}$

Step 3.3

The variable $j$ got canceled.

All real numbers

$i = - \frac{v}{7} - \frac{2 j}{7}$

All real numbers

$i = - \frac{v}{7} - \frac{2 j}{7}$