3.91x10^-2 in standard form

Pls me this is due today and i need i will make brainliest if you me answer correctly and i will report if you try to give me a dumb answer.

After being rearranged and simplified, which of the following equations could be solved using the quadratic formula? check all that apply. a. 9% + 3x2 = 14 + x-1 b. -x+ + 4x + 7 = -32-9 c. 5x + 4 = 3x4 - 2 d. 2x2 + x2 + x = 30

Which of the following is not a subset of {1,2,3}?