Quadratic Formula

[mathdad]

Solving ax^2 + bx + c = 0 for x leads to the quadratic formula. In the formula itself, where does 4 and 2 come from?

 

[MarkFL]

Try solving it by completing the square. Then you'll see for yourself exactly where everything comes from. It's a good exercise too.

 

[Steven G]

ax^2 + bx + c = 0
ax^2 + bx = -c
x^2 + (b/a)x = -c/a
Continue with completing the square.

 

[mathdad]

Ok. I will do so on paper only.