To the nearest tenth, what's the circumference of a circular pond with a radius of 14 meters?

Icould really use some with this question.

Determine the required value of the missing probability to make the distribution a discrete probability distribution. x p(x) 3 0.23 4 ? 5 0.51 6 0.08 p(4) = nothing  (type an integer or a decimal.)

Write the factored form of this trinomial 9x^2+18x-7