Algebra Examples

$m (x) = - x (x - 4)$

Step 1

Apply the distributive property.

$m (x) = - x \cdot x - x \cdot - 4$

Step 2

Multiply $x$ by $x$ by adding the exponents.

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Step 2.1

Move $x$ .

$m (x) = - (x \cdot x) - x \cdot - 4$

Step 2.2

Multiply $x$ by $x$ .

$m (x) = - x^{2} - x \cdot - 4$

Step 3

Multiply $- 4$ by $- 1$ .

$m (x) = - x^{2} + 4 x$

Step 4

The maximum of a quadratic function occurs at $x = - \frac{b}{2 a}$ . If $a$ is negative, the maximum value of the function is $f (- \frac{b}{2 a})$ .

$f_{max}$ $x = a x^{2} + b x + c$ occurs at $x = - \frac{b}{2 a}$

Step 5

Find the value of $x = - \frac{b}{2 a}$ .

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Step 5.1

Substitute in the values of $a$ and $b$ .

$x = - \frac{4}{2 (- 1)}$

Step 5.2

Remove parentheses.

$x = - \frac{4}{2 (- 1)}$

Step 5.3

Simplify $- \frac{4}{2 (- 1)}$ .

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Step 5.3.1

Cancel the common factor of $4$ and $2$ .

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Step 5.3.1.1

Factor $2$ out of $4$ .

$x = - \frac{2 \cdot 2}{2 \cdot - 1}$

Step 5.3.1.2

Move the negative one from the denominator of $\frac{2}{- 1}$ .

$x = - (- 1 \cdot 2)$

Step 5.3.2

Multiply $- (- 1 \cdot 2)$ .

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Step 5.3.2.1

Multiply $- 1$ by $2$ .

$x = - - 2$

Step 5.3.2.2

Multiply $- 1$ by $- 2$ .

$x = 2$

Step 6

Evaluate $f (2)$ .

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Step 6.1

Replace the variable $x$ with $2$ in the expression.

$m (2) = - {(2)}^{2} + 4 (2)$

Step 6.2

Simplify the result.

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Step 6.2.1

Simplify each term.

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Step 6.2.1.1

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

$m (2) = - 1 \cdot 4 + 4 (2)$

Step 6.2.1.2

Multiply $- 1$ by $4$ .

$m (2) = - 4 + 4 (2)$

Step 6.2.1.3

Multiply $4$ by $2$ .

$m (2) = - 4 + 8$

Step 6.2.2

Add $- 4$ and $8$ .

$m (2) = 4$

Step 6.2.3

The final answer is $4$ .

$4$

Step 7

Use the $x$ and $y$ values to find where the maximum occurs.

$(2, 4)$

Step 8