For example, when m is what value, there are two equal real roots about the binary linear equation x2-4x+m- 1/2 = 0? What is a real root? Because the equation has two equal real roots, delta = b' 2-4ac =16-4 [m-(1/2)] = 0, and the solution is m=9/2. Substitute it into the equation x'2-4x+4=0, and the solution is x=2.