What are the coefficients in the algebraic expression

Will give brainliest series to sigma notation write the following series in sigma notation. 6+10+14+18+22+26+30 example image shown below.

With number 11 ( show how you got the answer)

Pleting the square f the given find the x-intercepts of the parabola with vertex (-5,13) and y-intercept (0, 12). write your answer in this form: (14,.99). if necessary, round to the nearest hundredth. *- h enter the correct answer, de verter, and ametry 00000 done doo