Precalculus Examples

$\sum_{k = 1}^{4} 2 k$

Step 1

The formula for the summation of a polynomial with degree $1$ is:

$\sum_{k = 1}^{n} k = \frac{n (n + 1)}{2}$

Step 2

Substitute the values into the formula and make sure to multiply by the front term.

$(2) (\frac{4 (4 + 1)}{2})$

Step 3

Simplify.

Tap for more steps...

Step 3.1

Simplify the expression.

Tap for more steps...

Step 3.1.1

Add $4$ and $1$ .

$2 \frac{4 \cdot 5}{2}$

Step 3.1.2

Multiply $4$ by $5$ .

$2 (\frac{20}{2})$

Step 3.2

Cancel the common factor of $2$ .

Tap for more steps...

Step 3.2.1

Cancel the common factor.

$2 (\frac{20}{2})$

Step 3.2.2

Rewrite the expression.

$20$