Calculus Examples

$f (x) = x^{3} - 3 x^{2}$ , $g (x) = 3 x^{2} - 1$

Step 1

Set up the composite result function.

$f (g (x))$

Step 2

Evaluate $f (3 x^{2} - 1)$ by substituting in the value of $g$ into $f$ .

$f (3 x^{2} - 1) = {(3 x^{2} - 1)}^{3} - 3 {(3 x^{2} - 1)}^{2}$

Step 3

Simplify each term.

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Step 3.1

Use the Binomial Theorem.

$f (3 x^{2} - 1) = {(3 x^{2})}^{3} + 3 {(3 x^{2})}^{2} \cdot - 1 + 3 (3 x^{2}) {(- 1)}^{2} + {(- 1)}^{3} - 3 {(3 x^{2} - 1)}^{2}$

Step 3.2

Simplify each term.

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Step 3.2.1

Apply the product rule to $3 x^{2}$ .

$f (3 x^{2} - 1) = 3^{3} {(x^{2})}^{3} + 3 {(3 x^{2})}^{2} \cdot - 1 + 3 (3 x^{2}) {(- 1)}^{2} + {(- 1)}^{3} - 3 {(3 x^{2} - 1)}^{2}$

Step 3.2.2

Raise $3$ to the power of $3$ .

$f (3 x^{2} - 1) = 27 {(x^{2})}^{3} + 3 {(3 x^{2})}^{2} \cdot - 1 + 3 (3 x^{2}) {(- 1)}^{2} + {(- 1)}^{3} - 3 {(3 x^{2} - 1)}^{2}$

Step 3.2.3

Multiply the exponents in ${(x^{2})}^{3}$ .

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Step 3.2.3.1

Apply the power rule and multiply exponents, ${(a^{m})}^{n} = a^{m n}$ .

$f (3 x^{2} - 1) = 27 x^{2 \cdot 3} + 3 {(3 x^{2})}^{2} \cdot - 1 + 3 (3 x^{2}) {(- 1)}^{2} + {(- 1)}^{3} - 3 {(3 x^{2} - 1)}^{2}$

Step 3.2.3.2

Multiply $2$ by $3$ .

$f (3 x^{2} - 1) = 27 x^{6} + 3 {(3 x^{2})}^{2} \cdot - 1 + 3 (3 x^{2}) {(- 1)}^{2} + {(- 1)}^{3} - 3 {(3 x^{2} - 1)}^{2}$

Step 3.2.4

Apply the product rule to $3 x^{2}$ .

$f (3 x^{2} - 1) = 27 x^{6} + 3 (3^{2} {(x^{2})}^{2}) \cdot - 1 + 3 (3 x^{2}) {(- 1)}^{2} + {(- 1)}^{3} - 3 {(3 x^{2} - 1)}^{2}$

Step 3.2.5

Multiply $3$ by $3^{2}$ by adding the exponents.

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Step 3.2.5.1

Move $3^{2}$ .

$f (3 x^{2} - 1) = 27 x^{6} + 3^{2} \cdot (3 {(x^{2})}^{2}) \cdot - 1 + 3 (3 x^{2}) {(- 1)}^{2} + {(- 1)}^{3} - 3 {(3 x^{2} - 1)}^{2}$

Step 3.2.5.2

Multiply $3^{2}$ by $3$ .

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Step 3.2.5.2.1

Raise $3$ to the power of $1$ .

$f (3 x^{2} - 1) = 27 x^{6} + 3^{2} \cdot (3 {(x^{2})}^{2}) \cdot - 1 + 3 (3 x^{2}) {(- 1)}^{2} + {(- 1)}^{3} - 3 {(3 x^{2} - 1)}^{2}$

Step 3.2.5.2.2

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

$f (3 x^{2} - 1) = 27 x^{6} + 3^{2 + 1} {(x^{2})}^{2} \cdot - 1 + 3 (3 x^{2}) {(- 1)}^{2} + {(- 1)}^{3} - 3 {(3 x^{2} - 1)}^{2}$

Step 3.2.5.3

Add $2$ and $1$ .

$f (3 x^{2} - 1) = 27 x^{6} + 3^{3} {(x^{2})}^{2} \cdot - 1 + 3 (3 x^{2}) {(- 1)}^{2} + {(- 1)}^{3} - 3 {(3 x^{2} - 1)}^{2}$

Step 3.2.6

Raise $3$ to the power of $3$ .

$f (3 x^{2} - 1) = 27 x^{6} + 27 {(x^{2})}^{2} \cdot - 1 + 3 (3 x^{2}) {(- 1)}^{2} + {(- 1)}^{3} - 3 {(3 x^{2} - 1)}^{2}$

Step 3.2.7

Multiply the exponents in ${(x^{2})}^{2}$ .

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Step 3.2.7.1

Apply the power rule and multiply exponents, ${(a^{m})}^{n} = a^{m n}$ .

$f (3 x^{2} - 1) = 27 x^{6} + 27 x^{2 \cdot 2} \cdot - 1 + 3 (3 x^{2}) {(- 1)}^{2} + {(- 1)}^{3} - 3 {(3 x^{2} - 1)}^{2}$

Step 3.2.7.2

Multiply $2$ by $2$ .

$f (3 x^{2} - 1) = 27 x^{6} + 27 x^{4} \cdot - 1 + 3 (3 x^{2}) {(- 1)}^{2} + {(- 1)}^{3} - 3 {(3 x^{2} - 1)}^{2}$

Step 3.2.8

Multiply $- 1$ by $27$ .

$f (3 x^{2} - 1) = 27 x^{6} - 27 x^{4} + 3 (3 x^{2}) {(- 1)}^{2} + {(- 1)}^{3} - 3 {(3 x^{2} - 1)}^{2}$

Step 3.2.9

Multiply $3$ by $3$ .

$f (3 x^{2} - 1) = 27 x^{6} - 27 x^{4} + 9 x^{2} {(- 1)}^{2} + {(- 1)}^{3} - 3 {(3 x^{2} - 1)}^{2}$

Step 3.2.10

Raise $- 1$ to the power of $2$ .

$f (3 x^{2} - 1) = 27 x^{6} - 27 x^{4} + 9 x^{2} \cdot 1 + {(- 1)}^{3} - 3 {(3 x^{2} - 1)}^{2}$

Step 3.2.11

Multiply $9$ by $1$ .

$f (3 x^{2} - 1) = 27 x^{6} - 27 x^{4} + 9 x^{2} + {(- 1)}^{3} - 3 {(3 x^{2} - 1)}^{2}$

Step 3.2.12

Raise $- 1$ to the power of $3$ .

$f (3 x^{2} - 1) = 27 x^{6} - 27 x^{4} + 9 x^{2} - 1 - 3 {(3 x^{2} - 1)}^{2}$

Step 3.3

Rewrite ${(3 x^{2} - 1)}^{2}$ as $(3 x^{2} - 1) (3 x^{2} - 1)$ .

$f (3 x^{2} - 1) = 27 x^{6} - 27 x^{4} + 9 x^{2} - 1 - 3 ((3 x^{2} - 1) (3 x^{2} - 1))$

Step 3.4

Expand $(3 x^{2} - 1) (3 x^{2} - 1)$ using the FOIL Method.

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Step 3.4.1

Apply the distributive property.

$f (3 x^{2} - 1) = 27 x^{6} - 27 x^{4} + 9 x^{2} - 1 - 3 (3 x^{2} (3 x^{2} - 1) - 1 (3 x^{2} - 1))$

Step 3.4.2

Apply the distributive property.

$f (3 x^{2} - 1) = 27 x^{6} - 27 x^{4} + 9 x^{2} - 1 - 3 (3 x^{2} (3 x^{2}) + 3 x^{2} \cdot - 1 - 1 (3 x^{2} - 1))$

Step 3.4.3

Apply the distributive property.

$f (3 x^{2} - 1) = 27 x^{6} - 27 x^{4} + 9 x^{2} - 1 - 3 (3 x^{2} (3 x^{2}) + 3 x^{2} \cdot - 1 - 1 (3 x^{2}) - 1 \cdot - 1)$

Step 3.5

Simplify and combine like terms.

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Step 3.5.1

Simplify each term.

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Step 3.5.1.1

Rewrite using the commutative property of multiplication.

$f (3 x^{2} - 1) = 27 x^{6} - 27 x^{4} + 9 x^{2} - 1 - 3 (3 \cdot (3 x^{2} x^{2}) + 3 x^{2} \cdot - 1 - 1 (3 x^{2}) - 1 \cdot - 1)$

Step 3.5.1.2

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

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Step 3.5.1.2.1

Move $x^{2}$ .

$f (3 x^{2} - 1) = 27 x^{6} - 27 x^{4} + 9 x^{2} - 1 - 3 (3 \cdot (3 (x^{2} x^{2})) + 3 x^{2} \cdot - 1 - 1 (3 x^{2}) - 1 \cdot - 1)$

Step 3.5.1.2.2

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

$f (3 x^{2} - 1) = 27 x^{6} - 27 x^{4} + 9 x^{2} - 1 - 3 (3 \cdot (3 x^{2 + 2}) + 3 x^{2} \cdot - 1 - 1 (3 x^{2}) - 1 \cdot - 1)$

Step 3.5.1.2.3

Add $2$ and $2$ .

$f (3 x^{2} - 1) = 27 x^{6} - 27 x^{4} + 9 x^{2} - 1 - 3 (3 \cdot (3 x^{4}) + 3 x^{2} \cdot - 1 - 1 (3 x^{2}) - 1 \cdot - 1)$

Step 3.5.1.3

Multiply $3$ by $3$ .

$f (3 x^{2} - 1) = 27 x^{6} - 27 x^{4} + 9 x^{2} - 1 - 3 (9 x^{4} + 3 x^{2} \cdot - 1 - 1 (3 x^{2}) - 1 \cdot - 1)$

Step 3.5.1.4

Multiply $- 1$ by $3$ .

$f (3 x^{2} - 1) = 27 x^{6} - 27 x^{4} + 9 x^{2} - 1 - 3 (9 x^{4} - 3 x^{2} - 1 (3 x^{2}) - 1 \cdot - 1)$

Step 3.5.1.5

Multiply $3$ by $- 1$ .

$f (3 x^{2} - 1) = 27 x^{6} - 27 x^{4} + 9 x^{2} - 1 - 3 (9 x^{4} - 3 x^{2} - 3 x^{2} - 1 \cdot - 1)$

Step 3.5.1.6

Multiply $- 1$ by $- 1$ .

$f (3 x^{2} - 1) = 27 x^{6} - 27 x^{4} + 9 x^{2} - 1 - 3 (9 x^{4} - 3 x^{2} - 3 x^{2} + 1)$

Step 3.5.2

Subtract $3 x^{2}$ from $- 3 x^{2}$ .

$f (3 x^{2} - 1) = 27 x^{6} - 27 x^{4} + 9 x^{2} - 1 - 3 (9 x^{4} - 6 x^{2} + 1)$

Step 3.6

Apply the distributive property.

$f (3 x^{2} - 1) = 27 x^{6} - 27 x^{4} + 9 x^{2} - 1 - 3 (9 x^{4}) - 3 (- 6 x^{2}) - 3 \cdot 1$

Step 3.7

Simplify.

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Step 3.7.1

Multiply $9$ by $- 3$ .

$f (3 x^{2} - 1) = 27 x^{6} - 27 x^{4} + 9 x^{2} - 1 - 27 x^{4} - 3 (- 6 x^{2}) - 3 \cdot 1$

Step 3.7.2

Multiply $- 6$ by $- 3$ .

$f (3 x^{2} - 1) = 27 x^{6} - 27 x^{4} + 9 x^{2} - 1 - 27 x^{4} + 18 x^{2} - 3 \cdot 1$

Step 3.7.3

Multiply $- 3$ by $1$ .

$f (3 x^{2} - 1) = 27 x^{6} - 27 x^{4} + 9 x^{2} - 1 - 27 x^{4} + 18 x^{2} - 3$

Step 4

Simplify by adding terms.

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Step 4.1

Subtract $27 x^{4}$ from $- 27 x^{4}$ .

$f (3 x^{2} - 1) = 27 x^{6} - 54 x^{4} + 9 x^{2} - 1 + 18 x^{2} - 3$

Step 4.2

Add $9 x^{2}$ and $18 x^{2}$ .

$f (3 x^{2} - 1) = 27 x^{6} - 54 x^{4} + 27 x^{2} - 1 - 3$

Step 4.3

Subtract $3$ from $- 1$ .

$f (3 x^{2} - 1) = 27 x^{6} - 54 x^{4} + 27 x^{2} - 4$