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Factorize:. x^3+3x-2?
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Factorize:. x^3+3x-2?
The crucial step is to replace x with (w+1/w), and to solve for w. This leads to a sixth order equation in w, BUT, it's a sixth order equation that's easy to solve. Here are the details:

x^3 - 3 x + 2 = 
(w+1/w)^3 - 3(w+1/w) + 2 = 
w^3 + 3 w^2 (1/w) + 3 w (1/w)^2 + (1/w)^3 - 3 (w+1/w) + 2 = 
w^3 + 3 w + 3 (1/w) + (1/w3) - 3 (w+1/w) + 2 = 
w^3 + (1/w^3) + 2.
So x^3-3x+2=0 becomes w^3+1/w^3+2 = 0

This is a sixth order equation in w. The trick to solving it is to realize that it's really a quadratic in w^3. Replacing w^3 with z, we get:

z + 1/z + 2 = 0

ie z^2 + 1 + 2z = 0.

Solving the quadratic using (z^2 + 1 + 2z = (z+1)^2 ) you get z = -1.

So, w^3 = -1.

A solution to this is w = -1, which gives the solution x = w + 1/w = -1+1/-1 = -2.

Polynomial division now gives

x^3-3x+2 can be factored as (x+2)(x^2 - 2x + 1).

x^2 - 2x + 1 = (x-1)^2, so we have that the solutions are x = -2 and 1 (with multiplicity 2).

We could have used other solutions to w3 = -1. The three solutions are:

w = -1, 1/2 + i √3/2, 1/2 - i √3/2

Choosing w = 1/2 + i √3/2, we get the solution

x = w + 1/w = (1/2 + i √3/2) + (1/2 - i √3/2) = (1/2)+(1/2) = 1



Also, in this particular example, using complex numbers is optional. By choosing the w= -1 solution to w^3= -1 we successfully avoided dealing with them.
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Factorize:. x^3+3x-2?
Factorizing x^3 + 3x - 2

To factorize the given expression x^3 + 3x - 2, we need to find the factors that can be multiplied together to obtain the original expression. In this case, we are looking for a product of two binomials.

Step 1: Try to find a rational root using the Rational Root Theorem

The Rational Root Theorem states that if a polynomial has a rational root, then it can be expressed as the quotient of two factors: p/q, where p is a factor of the constant term (in this case, -2) and q is a factor of the leading coefficient (in this case, 1).

In this case, the factors of -2 are ±1 and ±2, and the factors of 1 are ±1. Therefore, the possible rational roots are ±1 and ±2.

Step 2: Test the possible rational roots using synthetic division

Using synthetic division, we can test each possible rational root to see if it is a factor of the given expression.

Let's start with x = 1:
1 | 1 0 3 -2
| 1 1 4
------------
1 1 4 2

Since the remainder is not zero, x = 1 is not a factor.

Next, let's try x = -1:
-1 | 1 0 3 -2
| -1 1 -4
-------------
1 -1 4 -6

Again, the remainder is not zero, so x = -1 is not a factor.

We can continue this process for x = 2 and x = -2, but we can save time by noticing that none of the possible rational roots are factors of the given expression.

Step 3: Apply the Factor Theorem

Since none of the rational roots are factors, we can conclude that the given expression is irreducible over the rational numbers. In other words, it cannot be factored into linear factors with rational coefficients.

Therefore, the factorization of x^3 + 3x - 2 is x^3 + 3x - 2 (irreducible over the rational numbers).
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