Precalculus Examples

$u = - 2 i + 5 j$ , $v = 4 i - 6 j$

Step 1

Reorder $- 2 i$ and $5 j$ .

$u = 5 j - 2 i$

$v = 4 i - 6 j$

Step 2

Solve the equation for $i$ .

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Rewrite the equation as $4 i - 6 j = v$ .

$4 i - 6 j = v$

$u = 5 j - 2 i$

Add $6 j$ to both sides of the equation.

$4 i = v + 6 j$

$u = 5 j - 2 i$

Divide each term in $4 i = v + 6 j$ by $4$ and simplify.

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Divide each term in $4 i = v + 6 j$ by $4$ .

$\frac{4 i}{4} = \frac{v}{4} + \frac{6 j}{4}$

$u = 5 j - 2 i$

Simplify the left side.

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Cancel the common factor of $4$ .

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Cancel the common factor.

$\frac{4 i}{4} = \frac{v}{4} + \frac{6 j}{4}$

$u = 5 j - 2 i$

Divide $i$ by $1$ .

$i = \frac{v}{4} + \frac{6 j}{4}$

$u = 5 j - 2 i$

$i = \frac{v}{4} + \frac{6 j}{4}$

$u = 5 j - 2 i$

$i = \frac{v}{4} + \frac{6 j}{4}$

$u = 5 j - 2 i$

Simplify the right side.

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Cancel the common factor of $6$ and $4$ .

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Factor $2$ out of $6 j$ .

$i = \frac{v}{4} + \frac{2 (3 j)}{4}$

$u = 5 j - 2 i$

Cancel the common factors.

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Factor $2$ out of $4$ .

$i = \frac{v}{4} + \frac{2 (3 j)}{2 (2)}$

$u = 5 j - 2 i$

Cancel the common factor.

$i = \frac{v}{4} + \frac{2 (3 j)}{2 \cdot 2}$

$u = 5 j - 2 i$

Rewrite the expression.

$i = \frac{v}{4} + \frac{3 j}{2}$

$u = 5 j - 2 i$

$i = \frac{v}{4} + \frac{3 j}{2}$

$u = 5 j - 2 i$

$i = \frac{v}{4} + \frac{3 j}{2}$

$u = 5 j - 2 i$

$i = \frac{v}{4} + \frac{3 j}{2}$

$u = 5 j - 2 i$

$i = \frac{v}{4} + \frac{3 j}{2}$

$u = 5 j - 2 i$

$i = \frac{v}{4} + \frac{3 j}{2}$

$u = 5 j - 2 i$

Step 3

Solve the equation for $j$ .

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Simplify $5 j - 2 (\frac{v}{4} + \frac{3 j}{2})$ .

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Simplify each term.

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Apply the distributive property.

$5 j - 2 \frac{v}{4} - 2 \frac{3 j}{2} = - 2 (\frac{v}{4} + \frac{3 j}{2}) + 5 j$

$i = \frac{v}{4} + \frac{3 j}{2}$

Cancel the common factor of $2$ .

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Factor $2$ out of $- 2$ .

$5 j + 2 (- 1) (\frac{v}{4}) - 2 \frac{3 j}{2} = - 2 (\frac{v}{4} + \frac{3 j}{2}) + 5 j$

$i = \frac{v}{4} + \frac{3 j}{2}$

Factor $2$ out of $4$ .

$5 j + 2 \cdot (- 1 \frac{v}{2 \cdot 2}) - 2 \frac{3 j}{2} = - 2 (\frac{v}{4} + \frac{3 j}{2}) + 5 j$

$i = \frac{v}{4} + \frac{3 j}{2}$

Cancel the common factor.

$5 j + 2 \cdot (- 1 \frac{v}{2 \cdot 2}) - 2 \frac{3 j}{2} = - 2 (\frac{v}{4} + \frac{3 j}{2}) + 5 j$

$i = \frac{v}{4} + \frac{3 j}{2}$

Rewrite the expression.

$5 j - 1 \frac{v}{2} - 2 \frac{3 j}{2} = - 2 (\frac{v}{4} + \frac{3 j}{2}) + 5 j$

$i = \frac{v}{4} + \frac{3 j}{2}$

$5 j - 1 \frac{v}{2} - 2 \frac{3 j}{2} = - 2 (\frac{v}{4} + \frac{3 j}{2}) + 5 j$

$i = \frac{v}{4} + \frac{3 j}{2}$

Cancel the common factor of $2$ .

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Factor $2$ out of $- 2$ .

$5 j - 1 \frac{v}{2} + 2 (- 1) (\frac{3 j}{2}) = - 2 (\frac{v}{4} + \frac{3 j}{2}) + 5 j$

$i = \frac{v}{4} + \frac{3 j}{2}$

Cancel the common factor.

$5 j - 1 \frac{v}{2} + 2 \cdot (- 1 \frac{3 j}{2}) = - 2 (\frac{v}{4} + \frac{3 j}{2}) + 5 j$

$i = \frac{v}{4} + \frac{3 j}{2}$

Rewrite the expression.

$5 j - 1 \frac{v}{2} - 1 (3 j) = - 2 (\frac{v}{4} + \frac{3 j}{2}) + 5 j$

$i = \frac{v}{4} + \frac{3 j}{2}$

$5 j - 1 \frac{v}{2} - 1 (3 j) = - 2 (\frac{v}{4} + \frac{3 j}{2}) + 5 j$

$i = \frac{v}{4} + \frac{3 j}{2}$

Multiply $3$ by $- 1$ .

$5 j - 1 \frac{v}{2} - 3 j = - 2 (\frac{v}{4} + \frac{3 j}{2}) + 5 j$

$i = \frac{v}{4} + \frac{3 j}{2}$

Rewrite $- 1 \frac{v}{2}$ as $- \frac{v}{2}$ .

$5 j - \frac{v}{2} - 3 j = - 2 (\frac{v}{4} + \frac{3 j}{2}) + 5 j$

$i = \frac{v}{4} + \frac{3 j}{2}$

$5 j - \frac{v}{2} - 3 j = - 2 (\frac{v}{4} + \frac{3 j}{2}) + 5 j$

$i = \frac{v}{4} + \frac{3 j}{2}$

Subtract $3 j$ from $5 j$ .

$2 j - \frac{v}{2} = - 2 (\frac{v}{4} + \frac{3 j}{2}) + 5 j$

$i = \frac{v}{4} + \frac{3 j}{2}$

$2 j - \frac{v}{2} = - 2 (\frac{v}{4} + \frac{3 j}{2}) + 5 j$

$i = \frac{v}{4} + \frac{3 j}{2}$

Simplify $- 2 (\frac{v}{4} + \frac{3 j}{2}) + 5 j$ .

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Simplify each term.

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Apply the distributive property.

$2 j - \frac{v}{2} = - 2 \frac{v}{4} - 2 \frac{3 j}{2} + 5 j$

$i = \frac{v}{4} + \frac{3 j}{2}$

Cancel the common factor of $2$ .

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Factor $2$ out of $- 2$ .

$2 j - \frac{v}{2} = 2 (- 1) (\frac{v}{4}) - 2 \frac{3 j}{2} + 5 j$

$i = \frac{v}{4} + \frac{3 j}{2}$

Factor $2$ out of $4$ .

$2 j - \frac{v}{2} = 2 \cdot (- 1 \frac{v}{2 \cdot 2}) - 2 \frac{3 j}{2} + 5 j$

$i = \frac{v}{4} + \frac{3 j}{2}$

Cancel the common factor.

$2 j - \frac{v}{2} = 2 \cdot (- 1 \frac{v}{2 \cdot 2}) - 2 \frac{3 j}{2} + 5 j$

$i = \frac{v}{4} + \frac{3 j}{2}$

Rewrite the expression.

$2 j - \frac{v}{2} = - 1 \frac{v}{2} - 2 \frac{3 j}{2} + 5 j$

$i = \frac{v}{4} + \frac{3 j}{2}$

$2 j - \frac{v}{2} = - 1 \frac{v}{2} - 2 \frac{3 j}{2} + 5 j$

$i = \frac{v}{4} + \frac{3 j}{2}$

Cancel the common factor of $2$ .

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Factor $2$ out of $- 2$ .

$2 j - \frac{v}{2} = - 1 \frac{v}{2} + 2 (- 1) (\frac{3 j}{2}) + 5 j$

$i = \frac{v}{4} + \frac{3 j}{2}$

Cancel the common factor.

$2 j - \frac{v}{2} = - 1 \frac{v}{2} + 2 \cdot (- 1 \frac{3 j}{2}) + 5 j$

$i = \frac{v}{4} + \frac{3 j}{2}$

Rewrite the expression.

$2 j - \frac{v}{2} = - 1 \frac{v}{2} - 1 (3 j) + 5 j$

$i = \frac{v}{4} + \frac{3 j}{2}$

$2 j - \frac{v}{2} = - 1 \frac{v}{2} - 1 (3 j) + 5 j$

$i = \frac{v}{4} + \frac{3 j}{2}$

Multiply $3$ by $- 1$ .

$2 j - \frac{v}{2} = - 1 \frac{v}{2} - 3 j + 5 j$

$i = \frac{v}{4} + \frac{3 j}{2}$

Rewrite $- 1 \frac{v}{2}$ as $- \frac{v}{2}$ .

$2 j - \frac{v}{2} = - \frac{v}{2} - 3 j + 5 j$

$i = \frac{v}{4} + \frac{3 j}{2}$

$2 j - \frac{v}{2} = - \frac{v}{2} - 3 j + 5 j$

$i = \frac{v}{4} + \frac{3 j}{2}$

Add $- 3 j$ and $5 j$ .

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

$i = \frac{v}{4} + \frac{3 j}{2}$

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

$i = \frac{v}{4} + \frac{3 j}{2}$

Move all terms containing $j$ to the left side of the equation.

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Subtract $2 j$ from both sides of the equation.

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

$i = \frac{v}{4} + \frac{3 j}{2}$

Combine the opposite terms in $2 j - \frac{v}{2} - 2 j$ .

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Subtract $2 j$ from $2 j$ .

$- \frac{v}{2} + 0 = - \frac{v}{2}$

$i = \frac{v}{4} + \frac{3 j}{2}$

Add $- \frac{v}{2}$ and $0$ .

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

$i = \frac{v}{4} + \frac{3 j}{2}$

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

$i = \frac{v}{4} + \frac{3 j}{2}$

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

$i = \frac{v}{4} + \frac{3 j}{2}$

Since the expression on each side of the equation has the same denominator, the numerators must be equal.

$- v = - v$

$i = \frac{v}{4} + \frac{3 j}{2}$

Move all terms containing $v$ to the left side of the equation.

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Add $v$ to both sides of the equation.

$- v + v = 0$

$i = \frac{v}{4} + \frac{3 j}{2}$

Add $- v$ and $v$ .

$0 = 0$

$i = \frac{v}{4} + \frac{3 j}{2}$

$0 = 0$

$i = \frac{v}{4} + \frac{3 j}{2}$

Since $0 = 0$ , the equation will always be true.

Always true

$i = \frac{v}{4} + \frac{3 j}{2}$

Always true

$i = \frac{v}{4} + \frac{3 j}{2}$

Step 4

Simplify the right side.

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Reorder $\frac{v}{4}$ and $\frac{3 j}{2}$ .

$i = \frac{3 j}{2} + \frac{v}{4}$

Always true

$i = \frac{3 j}{2} + \frac{v}{4}$

Always true