Why is math the hardest subject in the assortment of of other subject

it not hard but simplest of all subject just because of the workings that is under it and the thing is if u don't use common sense u won't just get the answer.

a complex number is a number that can be expressed in the form a + bi, where a and b are real numbers, and i is a solution of the equation x2 = −1. because no real number satisfies this equation, i is called an imaginary number. has no real solution, since the square of a real number cannot be negative.