Astudent guesses on every question of a multiple choice test that has 8 questions

Which is equivalent to 10/12? options: 10/18 5/6 3/12 9/11

Parabolas y=−2x^2 and y=2x^2 +k intersect at points a and b that are in the third and the fourth quadrants respectively. find k if length of the segment ab is 5.

How can i differentiate this equation?