(a+b+c)(b+c-a)(c+a-b)(a+b-c)

3 min read Jun 16, 2024
(a+b+c)(b+c-a)(c+a-b)(a+b-c)

Factoring and Simplifying (a+b+c)(b+c-a)(c+a-b)(a+b-c)

This expression appears complex, but it can be simplified significantly using basic algebraic techniques. Here's how we can factor and simplify it:

Understanding the Structure

The expression consists of four factors, each of which is a sum or difference of three variables:

  • (a + b + c)
  • (b + c - a)
  • (c + a - b)
  • (a + b - c)

Notice that each factor has two positive terms and one negative term. This suggests a pattern we can exploit.

Factoring by Grouping

We can rewrite the expression to make the pattern more evident:

  1. Rearrange the factors: Group the terms with the same sign together:

    (a + b + c)(b + c - a)(c + a - b)(a + b - c) = 
    [(a + b) + c][(b + c) - a][(c + a) - b][(a + b) - c] 
    
  2. Apply the difference of squares pattern: Recall that (x + y)(x - y) = x² - y². We can apply this pattern to the first two factors and the last two factors:

    [(a + b) + c][(b + c) - a][(c + a) - b][(a + b) - c] = 
    [((a + b)² - c²)][((c + a)² - b²)] 
    
  3. Expand the squares:

    [((a + b)² - c²)][((c + a)² - b²)] = 
    [(a² + 2ab + b² - c²)][(c² + 2ac + a² - b²)] 
    
  4. Rearrange the terms: Group the terms with common variables:

    [(a² + 2ab + b² - c²)][(c² + 2ac + a² - b²)] = 
    [(a² + 2ab + b² - c²) + (c² + 2ac + a² - b²)] 
    
  5. Combine like terms:

    [(a² + 2ab + b² - c²) + (c² + 2ac + a² - b²)] = 
    2a² + 2ab + 2ac + 2b² + 2c² 
    
  6. Factor out a 2:

    2a² + 2ab + 2ac + 2b² + 2c² = 2(a² + ab + ac + b² + c²)
    

Final Result

Therefore, the simplified form of the expression is: 2(a² + ab + ac + b² + c²). This expression cannot be further factored using real numbers.

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