solving quadratic equation in short time

A quadratic equation is very important for a student who studies in 10th std or competitive exam.

I learned one. I've searched before and not so many people know about it, so I'm helping you guys now. It's simple, but it has two rules. Considering this well-known equation:

ax² +bx +c = 0

Rule 1: A needs to have exactly the value 1. If the value is like 2 or 1/2, this trick will not work.

Rule 2: The two numbers need to be used in the two equations, with no change.

So, it is basically 

x1 + x2 = -b (x1 and x2 are the two answers you will get if you use the formula

x1 * x2 = c

Your goal is to guess the numbers that work in both of the equations. If it fits in both of them, then it is the two correct answers.

Example:

x² -5x +6 = 0

x1 + x2 = -(-5) = 5

x1 * x2 = 6

guessing value of x1 and x2 to be used in both equations.

3 + 2 = 5 (Correct)

3 * 2 = 6 (Correct)

This means that

x1 = 3

x2 = 2

it is answer

I hope this helps!