Monday, March 10, 2014

Solve for real and complex solutions.Integral of 4x^3+6x =10

To determine all real and complex solutions of the
equation, we'll have to determine the indefinite integral from the left side, for the
beginning.


Int (4x^3+6x)dx = 4Int x^3 dx + 6Int x
dx


Int (4x^3+6x)dx = 4x^4/4 + 6x^2/2 +
C


Int (4x^3+6x)dx = x^4 +
3x^2


We'll substitute the integral from the left side by
it's result:


x^4 + 3x^2 =
10


We'll subtract 10 both
sides:


x^4 + 3x^2 - 10 = 0


It
is a bi-quadratic equation. We'll put x^2 = t.


t^2 + 3t -
10 = 0


We'll apply quadratic
formula:


t1 =
[-3+sqrt(9+40)]/2


t1 =
(-3+7)/2


t1 = 2


t2 =
(-3-7)/2


t2 = -5


x^2 = t1
=> x^2 = 2


We'll take square root both
sides:


x1 = -sqrt2


x2 =
sqrt2


x^2 = t2 => x^2 =
-5


We'll take square root both
sides:


x3 = -isqrt5


x4 =
isqrt5


The real and complex roots of the
given equation are; {-sqrt2 ; sqrt2 ; -isqrt5 ;
isqrt5}.

No comments:

Post a Comment

Can (sec x - cosec x) / (tan x - cot x) be simplified further?

Given the expression ( sec x - csec x ) / (tan x - cot x) We need to simplify. We will use trigonometric identities ...