Precalculus Examples

$f (3) = 2 x^{4} - 8 x^{2} + 5 x - 7$

Step 1

Replace the variable $x$ with $3$ in the expression.

$f (3) = 2 {(3)}^{4} - 8 {(3)}^{2} + 5 (3) - 7$

Step 2

Simplify the result.

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Step 2.1

Simplify each term.

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Step 2.1.1

Raise $3$ to the power of $4$ .

$f (3) = 2 \cdot 81 - 8 {(3)}^{2} + 5 (3) - 7$

Step 2.1.2

Multiply $2$ by $81$ .

$f (3) = 162 - 8 {(3)}^{2} + 5 (3) - 7$

Step 2.1.3

Raise $3$ to the power of $2$ .

$f (3) = 162 - 8 \cdot 9 + 5 (3) - 7$

Step 2.1.4

Multiply $- 8$ by $9$ .

$f (3) = 162 - 72 + 5 (3) - 7$

Step 2.1.5

Multiply $5$ by $3$ .

$f (3) = 162 - 72 + 15 - 7$

$f (3) = 162 - 72 + 15 - 7$

Step 2.2

Simplify by adding and subtracting.

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Step 2.2.1

Subtract $72$ from $162$ .

$f (3) = 90 + 15 - 7$

Step 2.2.2

Add $90$ and $15$ .

$f (3) = 105 - 7$

Step 2.2.3

Subtract $7$ from $105$ .

$f (3) = 98$

$f (3) = 98$

Step 2.3

The final answer is $98$ .

$98$

$98$

Step 3

$[\begin{array}{c} x^{2} & \frac{1}{2} \\ \sqrt{π} & \int x d x \end{array}]$