Example

Subtracting 3x1x25x626x\frac{3x-1}{x^2-5x-6} - \frac{2}{6-x}

Subtract two rational expressions where one denominator is the opposite of a binomial factor of the other: 3x1x25x626x\frac{3x - 1}{x^2 - 5x - 6} - \frac{2}{6 - x}

Step 1 — Factor the denominator and resolve the opposites. Factor the first denominator: x25x6=(x6)(x+1)x^2 - 5x - 6 = (x - 6)(x + 1). The second denominator is 6x6 - x. Because x6x - 6 and 6x6 - x are opposites, multiply the second fraction by 11\frac{-1}{-1}: 26x11=2x6\frac{2}{6 - x} \cdot \frac{-1}{-1} = \frac{-2}{x - 6} Rewrite the subtraction: 3x1(x6)(x+1)2x6\frac{3x - 1}{(x - 6)(x + 1)} - \frac{-2}{x - 6}

Step 2 — Simplify the signs. Subtracting a negative is the same as adding a positive: 3x1(x6)(x+1)+2x6\frac{3x - 1}{(x - 6)(x + 1)} + \frac{2}{x - 6}

Step 3 — Find the LCD and rewrite. The LCD is (x6)(x+1)(x - 6)(x + 1). The first fraction already has the LCD. Multiply the numerator and denominator of the second fraction by (x+1)(x + 1): 3x1(x6)(x+1)+2(x+1)(x6)(x+1)\frac{3x - 1}{(x - 6)(x + 1)} + \frac{2(x + 1)}{(x - 6)(x + 1)} Distribute the 22 in the second numerator: 2(x+1)=2x+22(x + 1) = 2x + 2. 3x1(x6)(x+1)+2x+2(x6)(x+1)\frac{3x - 1}{(x - 6)(x + 1)} + \frac{2x + 2}{(x - 6)(x + 1)}

Step 4 — Add the numerators. Combine the numerators over the common denominator: 3x1+2x+2(x6)(x+1)\frac{3x - 1 + 2x + 2}{(x - 6)(x + 1)} Combine like terms to get the simplified result: 5x+1(x6)(x+1)\frac{5x + 1}{(x - 6)(x + 1)}

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Updated 2026-04-30

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