(x-1)(x-2)(x+3)(x+4)-84

4 min read Jun 17, 2024
(x-1)(x-2)(x+3)(x+4)-84

Factoring and Solving the Expression (x-1)(x-2)(x+3)(x+4)-84

This article explores the process of factoring and solving the expression (x-1)(x-2)(x+3)(x+4)-84. We will utilize algebraic manipulation and factoring techniques to simplify the expression and find its roots.

1. Recognizing the Pattern

Observe that the first four terms of the expression resemble a product of four binomials. This suggests a potential pattern that can be exploited for factoring.

2. Rearranging and Grouping

Let's rearrange the terms and group them strategically:

(x-1)(x+3)(x-2)(x+4) - 84

We can now see a more apparent pattern: the product of two pairs of binomials.

3. Expanding the Groups

Expand each group of binomials:

[(x² + 2x - 3)][(x² + 2x - 8)] - 84 

Notice that both expressions within the brackets share the same quadratic term, x² + 2x.

4. Substitution for Simplification

To make the expression more manageable, let's substitute y = x² + 2x:

(y - 3)(y - 8) - 84 

5. Expanding and Factoring

Expand the product and simplify:

y² - 11y + 24 - 84 
= y² - 11y - 60

Now, we can factor the quadratic:

(y - 15)(y + 4) 

6. Resubstituting and Solving

Substitute back y = x² + 2x:

(x² + 2x - 15)(x² + 2x + 4)

Now we have two quadratic expressions. We can factor each one further:

[(x + 5)(x - 3)][(x² + 2x + 4)]

The second quadratic expression (x² + 2x + 4) doesn't factor further using real numbers.

Therefore, the factored form of the original expression is:

(x + 5)(x - 3)(x² + 2x + 4)

7. Finding the Roots

To find the roots, we need to solve for x when the expression equals zero:

(x + 5)(x - 3)(x² + 2x + 4) = 0

This gives us three possible solutions:

  • x + 5 = 0 => x = -5
  • x - 3 = 0 => x = 3
  • x² + 2x + 4 = 0 (This quadratic has no real roots)

Therefore, the real roots of the expression are x = -5 and x = 3.

Conclusion

By carefully rearranging, grouping, and applying substitution, we successfully factored the expression (x-1)(x-2)(x+3)(x+4)-84. This process revealed the real roots of the expression, which are x = -5 and x = 3. This exercise demonstrates how strategic manipulation and factoring techniques can simplify complex expressions and lead to valuable insights.

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