Q&A for How to Derive the Quadratic Formula

Shown in the introduction above, it's a tool used to solve a quadratic equation that is not easily solved by factoring.

It's a formula for solving cubic equations. Take a look at math.vanderbilt.edu/schectex/courses/cubic/.

When you take the square root of both sides of the equation, you need a plus or minus sign before the right side to show that the positive value squared equals (x+b/2a)² and that the negative value squared equals (x+b/2a)².The square root of x², for example, does not equal x but rather equals the absolute value of x, so the right side may be positive or negative.

This is in quadratic ax^2 + bx + c form, where a is 19, b is 0 and c is 3. Subtract 3 from both sides of the equation: 19x^2 = -3. Divide both sides by 19: x^2 = -3/19. Take the square root on both sides. x = +/- (root 3)i/square root of 19.