Precalculus Examples

$\sum_{x = 1}^{20} 5^{2 - n}$

Step 1

The formula for the summation of a constant is:

$\sum_{k = 1}^{n} c = c n$

Step 2

Substitute the values into the formula.

$(5^{2 - n}) (20)$

Step 3

Move $20$ to the left of $5^{2 - n}$ .

$20 \cdot 5^{2 - n}$

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