Saturday, November 6, 2010

Solve the binomial equation x^3 + 8 = 0

To solve the binomial equation, we'll apply the formula of
the sum of cubes:


a^3 + b^3 = (a+b)(a^2 - ab +
b^2)


a^3 = x^3


a =
x


b^3 = 2^3 = 8


b =
2


x^3 + 8 = (x+2)(x^2 - 2x +
4)


If x^3 + 8 = 0, then (x+2)(x^2 - 2x + 4) =
0


If a product is zero, then each factor could be
zero.


x + 2 = 0


We'll subtract
2 both sides:


x1 =
-2


x^2 - 2x + 4 =
0


We'll apply the quadratic
formula:


x2 = [2 +
sqrt(4-16)]/2


x2 =
(2+2isqrt3)/2


We'll factorize by
2:


x2 =
2(1+isqrt3)/2


x2 =
1+isqrt3


x3 = 1-
isqrt3


The roots of the
equation are: {-2 , 1+isqrt3, 1- isqrt3 }.

No comments:

Post a Comment

How is Anne's goal of wanting "to go on living even after my death" fulfilled in Anne Frank: The Diary of a Young Girl?I didn't get how it was...

I think you are right! I don't believe that many of the Jews who were herded into the concentration camps actually understood the eno...