Question

Determine the sum of the arithmetic series 6 + 11 + 16 +......
91.

Answer 1

873

Explanation:

so the equation is: 5x+1

sum is:

`(first \: one \: + \: last \: one)/(2) * quantity \: of \: terms \\`

we have 6( 5×1+1) to 91 (5×18+1)

so we have 18 terms

then:

`(91 + 6)/(2) * 18 = 873`