Simplify the following expression: 2/(x-3) + 5/(x+4) - 7/(x+2)

Question image

Understand the Problem

The question requires us to simplify the expression by finding a common denominator and combining the fractions, then simplifying it to a single fraction.

Answer

$\frac{70}{(x-3)(x+4)(x+2)}$
Answer for screen readers

$\frac{70}{(x-3)(x+4)(x+2)}$

Steps to Solve

  1. Find a Common Denominator

The common denominator for the three fractions is the product of their individual denominators: $(x-3)(x+4)(x+2)$. We will rewrite each fraction with this common denominator.

  1. Rewrite Each Fraction
  • For the first fraction, $\frac{2}{x-3}$, multiply the numerator and denominator by $(x+4)(x+2)$: $$ \frac{2(x+4)(x+2)}{(x-3)(x+4)(x+2)} = \frac{2(x^2 + 6x + 8)}{(x-3)(x+4)(x+2)} = \frac{2x^2 + 12x + 16}{(x-3)(x+4)(x+2)} $$
  • For the second fraction, $\frac{5}{x+4}$, multiply the numerator and denominator by $(x-3)(x+2)$: $$ \frac{5(x-3)(x+2)}{(x-3)(x+4)(x+2)} = \frac{5(x^2 -x - 6)}{(x-3)(x+4)(x+2)} = \frac{5x^2 - 5x - 30}{(x-3)(x+4)(x+2)} $$
  • For the third fraction, $\frac{7}{x+2}$, multiply the numerator and denominator by $(x-3)(x+4)$: $$ \frac{7(x-3)(x+4)}{(x-3)(x+4)(x+2)} = \frac{7(x^2 + x - 12)}{(x-3)(x+4)(x+2)} = \frac{7x^2 + 7x - 84}{(x-3)(x+4)(x+2)} $$
  1. Combine the Fractions

Now, combine the fractions using the common denominator: $$ \frac{(2x^2 + 12x + 16) + (5x^2 - 5x - 30) - (7x^2 + 7x - 84)}{(x-3)(x+4)(x+2)} $$ Simplify the numerator: $$ \frac{2x^2 + 12x + 16 + 5x^2 - 5x - 30 - 7x^2 - 7x + 84}{(x-3)(x+4)(x+2)} $$ $$ \frac{(2x^2 + 5x^2 - 7x^2) + (12x - 5x - 7x) + (16 - 30 + 84)}{(x-3)(x+4)(x+2)} $$ $$ \frac{0x^2 + 0x + 70}{(x-3)(x+4)(x+2)} $$ $$ \frac{70}{(x-3)(x+4)(x+2)} $$

  1. Final Simplified Expression

The simplified expression is: $$ \frac{70}{(x-3)(x+4)(x+2)} $$

$\frac{70}{(x-3)(x+4)(x+2)}$

More Information

The final simplified form is $\frac{70}{(x-3)(x+4)(x+2)}$, which cannot be simplified further.

Tips

A common mistake is to forget to distribute the negative sign when combining the numerators, especially with the third fraction. Another common mistake is making errors when expanding the products in the numerator.

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