Question

Explain the quadratic formula and how to use it.

Answer 1

http://www.purplemath.com/modules/quadform.htm

Answer 2

The quadratic formula can be used to solve.. quadratic equations. A quadratic equation is defined by:
\[ax^{2}+bx+c^{2}\]
In the equation the coefficient is listed as a, b and a constant c.

The quadratic equation is:
\[x = -b \pm \sqrt{b^2-4ac}/2a\]

You just substitute in your coefficients and simplify the answer. You will get two answers. :)
For example:
x^2 +10x + 9
a = 1
b = 3
c = 9

\[x = -b \pm \sqrt{b^2-4ac}/2a\]

-10 +/- sqrt(10^2-4x1x9)/2x1
-10 +/- sqrt(100-36)/2x1
-10 +/- 8 /2

-10+ 8 /2 = -2/2 = -1
-10 - 8 /2 = -18/2 = -9

x = -1
or x = -9
I hope I didn't make any silly error here, excuse me if I did.

Answer 3

Oops, in the first equation it shouldn't be c^2, rather just c. sorry D:

Answer 4

for quadratic equation ax^2 +bx + c = 0, its two roots are found by what we call quadratic formula which is given below

x1=[-b+sqrt(b^2-4ac)] / 2a
x2= [-b-sqrt(b^2-4ac)] / 2a

x1 and x2 are two roots of quadratic equation ax^2 +bx + c = 0

for any given quadratic equation, compare the coefficients of x^2, x^1 and x^0(constant term of given equation) which are a, b and c respectively, and put them in above formula to get answer.