Find the 11th partial sum of the summation of negative 7i plus 22, from i equals 1 to infinity.

-220

400

550

-700

The answer is - 220

What you do is take - 7 and multiply that by (1+2+3+4+5+6+7+8+9+10+11) and then after that add 11 again and multiply it by 22. It would look like this.

-7 x (1+2+3+4+5+6+7+8+9+10+11) + 11 x 22

Simplify that to - 7 x 66 + 11 x 22

now multiply - 7 and 66 to get - 462

-462 + 11 x 22

multiply 11 and 22

-462 + 242

and your final answer will be - 220