Precalculus Examples

$\sum_{x = 1}^{7} x$

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.

$\frac{7 (7 + 1)}{2}$

Step 3

Simplify.

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Step 3.1

Add $7$ and $1$ .

$\frac{7 \cdot 8}{2}$

Step 3.2

Multiply $7$ by $8$ .

$\frac{56}{2}$

Step 3.3

Divide $56$ by $2$ .

$28$