In a direct variation equation, f(2)=6 when x = 4.
What is the direct variation equation?

 it could be f(x)= 3/2 x

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.