Algebra Examples

$f (x) = - \frac{1}{2} x^{2} + 5 x$ $g (x) = x^{2} + 2$

Step 1

Set up the composite result function.

$f (g (x))$

Step 2

Evaluate $f (x^{2} + 2)$ by substituting in the value of $g$ into $f$ .

$f (x^{2} + 2) = - \frac{1}{2} \cdot {(x^{2} + 2)}^{2} + 5 (x^{2} + 2)$

Step 3

Simplify each term.

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Step 3.1

Rewrite ${(x^{2} + 2)}^{2}$ as $(x^{2} + 2) (x^{2} + 2)$ .

$f (x^{2} + 2) = - \frac{1}{2} \cdot ((x^{2} + 2) (x^{2} + 2)) + 5 (x^{2} + 2)$

Step 3.2

Expand $(x^{2} + 2) (x^{2} + 2)$ using the FOIL Method.

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Step 3.2.1

Apply the distributive property.

$f (x^{2} + 2) = - \frac{1}{2} \cdot (x^{2} (x^{2} + 2) + 2 (x^{2} + 2)) + 5 (x^{2} + 2)$

Step 3.2.2

Apply the distributive property.

$f (x^{2} + 2) = - \frac{1}{2} \cdot (x^{2} x^{2} + x^{2} \cdot 2 + 2 (x^{2} + 2)) + 5 (x^{2} + 2)$

Step 3.2.3

Apply the distributive property.

$f (x^{2} + 2) = - \frac{1}{2} \cdot (x^{2} x^{2} + x^{2} \cdot 2 + 2 x^{2} + 2 \cdot 2) + 5 (x^{2} + 2)$

Step 3.3

Simplify and combine like terms.

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Step 3.3.1

Simplify each term.

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Step 3.3.1.1

Multiply $x^{2}$ by $x^{2}$ by adding the exponents.

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Step 3.3.1.1.1

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

$f (x^{2} + 2) = - \frac{1}{2} \cdot (x^{2 + 2} + x^{2} \cdot 2 + 2 x^{2} + 2 \cdot 2) + 5 (x^{2} + 2)$

Step 3.3.1.1.2

Add $2$ and $2$ .

$f (x^{2} + 2) = - \frac{1}{2} \cdot (x^{4} + x^{2} \cdot 2 + 2 x^{2} + 2 \cdot 2) + 5 (x^{2} + 2)$

Step 3.3.1.2

Move $2$ to the left of $x^{2}$ .

$f (x^{2} + 2) = - \frac{1}{2} \cdot (x^{4} + 2 \cdot x^{2} + 2 x^{2} + 2 \cdot 2) + 5 (x^{2} + 2)$

Step 3.3.1.3

Multiply $2$ by $2$ .

$f (x^{2} + 2) = - \frac{1}{2} \cdot (x^{4} + 2 x^{2} + 2 x^{2} + 4) + 5 (x^{2} + 2)$

Step 3.3.2

Add $2 x^{2}$ and $2 x^{2}$ .

$f (x^{2} + 2) = - \frac{1}{2} \cdot (x^{4} + 4 x^{2} + 4) + 5 (x^{2} + 2)$

Step 3.4

Apply the distributive property.

$f (x^{2} + 2) = - \frac{1}{2} x^{4} - \frac{1}{2} \cdot (4 x^{2}) - \frac{1}{2} \cdot 4 + 5 (x^{2} + 2)$

Step 3.5

Simplify.

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Step 3.5.1

Combine $x^{4}$ and $\frac{1}{2}$ .

$f (x^{2} + 2) = - \frac{x^{4}}{2} - \frac{1}{2} \cdot (4 x^{2}) - \frac{1}{2} \cdot 4 + 5 (x^{2} + 2)$

Step 3.5.2

Cancel the common factor of $2$ .

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Step 3.5.2.1

Move the leading negative in $- \frac{1}{2}$ into the numerator.

$f (x^{2} + 2) = - \frac{x^{4}}{2} + \frac{- 1}{2} \cdot (4 x^{2}) - \frac{1}{2} \cdot 4 + 5 (x^{2} + 2)$

Step 3.5.2.2

Factor $2$ out of $4 x^{2}$ .

$f (x^{2} + 2) = - \frac{x^{4}}{2} + \frac{- 1}{2} \cdot (2 (2 x^{2})) - \frac{1}{2} \cdot 4 + 5 (x^{2} + 2)$

Step 3.5.2.3

Cancel the common factor.

$f (x^{2} + 2) = - \frac{x^{4}}{2} + \frac{- 1}{2} \cdot (2 (2 x^{2})) - \frac{1}{2} \cdot 4 + 5 (x^{2} + 2)$

Step 3.5.2.4

Rewrite the expression.

$f (x^{2} + 2) = - \frac{x^{4}}{2} - 1 (2 x^{2}) - \frac{1}{2} \cdot 4 + 5 (x^{2} + 2)$

Step 3.5.3

Multiply $2$ by $- 1$ .

$f (x^{2} + 2) = - \frac{x^{4}}{2} - 2 x^{2} - \frac{1}{2} \cdot 4 + 5 (x^{2} + 2)$

Step 3.5.4

Cancel the common factor of $2$ .

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Step 3.5.4.1

Move the leading negative in $- \frac{1}{2}$ into the numerator.

$f (x^{2} + 2) = - \frac{x^{4}}{2} - 2 x^{2} + \frac{- 1}{2} \cdot 4 + 5 (x^{2} + 2)$

Step 3.5.4.2

Factor $2$ out of $4$ .

$f (x^{2} + 2) = - \frac{x^{4}}{2} - 2 x^{2} + \frac{- 1}{2} \cdot (2 (2)) + 5 (x^{2} + 2)$

Step 3.5.4.3

Cancel the common factor.

$f (x^{2} + 2) = - \frac{x^{4}}{2} - 2 x^{2} + \frac{- 1}{2} \cdot (2 \cdot 2) + 5 (x^{2} + 2)$

Step 3.5.4.4

Rewrite the expression.

$f (x^{2} + 2) = - \frac{x^{4}}{2} - 2 x^{2} - 1 \cdot 2 + 5 (x^{2} + 2)$

Step 3.5.5

Multiply $- 1$ by $2$ .

$f (x^{2} + 2) = - \frac{x^{4}}{2} - 2 x^{2} - 2 + 5 (x^{2} + 2)$

Step 3.6

Apply the distributive property.

$f (x^{2} + 2) = - \frac{x^{4}}{2} - 2 x^{2} - 2 + 5 x^{2} + 5 \cdot 2$

Step 3.7

Multiply $5$ by $2$ .

$f (x^{2} + 2) = - \frac{x^{4}}{2} - 2 x^{2} - 2 + 5 x^{2} + 10$

Step 4

Simplify by adding terms.

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Step 4.1

Add $- 2 x^{2}$ and $5 x^{2}$ .

$f (x^{2} + 2) = - \frac{x^{4}}{2} + 3 x^{2} - 2 + 10$

Step 4.2

Add $- 2$ and $10$ .

$f (x^{2} + 2) = - \frac{x^{4}}{2} + 3 x^{2} + 8$