Question

what is the sum of this arithmetic series? 586+564+542+...+212

Answer 1

Answer:

Basically it's asking for the sum of 212 + 216 + 220 + ..... 586

Each number is 22 more than the previous one.

Therefore the sum will be 212 + (212+22) + (212+22*2) + (212+22*3)

the amount of numbers from 212 through 586 is 18.

Therefore we will need 212 plus 212 * 17 = 3,816 *******************

We will also need all those 22's.

We must add 22 *1 plus 22*2 plus 22*3 ..... plus 22*17

Which equals 22 + 44 + 66 + 88 ... 374

Which totals 3,366 *****************

So, we total 3,816 + 3,366 which equals 7,182

Step-by-step explanation:

Answer 2

 

$\displaystyle\bf\\Sum=586+564+542+...+212\\\\Sum=212+234+256+...+586\\\\\textbf{We calculate the number of terms (n):}\\\\n=\frac{586-212}{22}+1=\frac{374}{22}+1=17+1=18\\\\\boxed{\bf~n=18~terms}\\\\Sum=\frac{n(586+212)}{2}\\\\Sum=\frac{18\times 798}{2}\\\\Sum=9\times798\\\\\boxed{\bf~Sum=7182}$