Solve 1/x^2-1-2/x^2+3x-4+1/x^2-2x-3

$$\frac { 1 } { x ^ { 2 } - 1 } - \frac { 2 } { x ^ { 2 } + 3 x - 4 } + \frac { 1 } { x ^ { 2 } - 2 x - 3 }$$

Evaluate

$$\frac{2\left(4x-5\right)}{\left(x-3\right)\left(x+4\right)\left(x^{2}-1\right)}$$

Short Solution Steps

Factor x^{2}-1. Factor x^{2}+3x-4.

$$\frac{1}{\left(x-1\right)\left(x+1\right)}-\frac{2}{\left(x-1\right)\left(x+4\right)}+\frac{1}{x^{2}-2x-3}$$

To add or subtract expressions, expand them to make their denominators the same. Least common multiple of \left(x-1\right)\left(x+1\right) and \left(x-1\right)\left(x+4\right) is \left(x-1\right)\left(x+1\right)\left(x+4\right). Multiply \frac{1}{\left(x-1\right)\left(x+1\right)} times \frac{x+4}{x+4}. Multiply \frac{2}{\left(x-1\right)\left(x+4\right)} times \frac{x+1}{x+1}.

$$\frac{x+4}{\left(x-1\right)\left(x+1\right)\left(x+4\right)}-\frac{2\left(x+1\right)}{\left(x-1\right)\left(x+1\right)\left(x+4\right)}+\frac{1}{x^{2}-2x-3}$$

Since \frac{x+4}{\left(x-1\right)\left(x+1\right)\left(x+4\right)} and \frac{2\left(x+1\right)}{\left(x-1\right)\left(x+1\right)\left(x+4\right)} have the same denominator, subtract them by subtracting their numerators.

$$\frac{x+4-2\left(x+1\right)}{\left(x-1\right)\left(x+1\right)\left(x+4\right)}+\frac{1}{x^{2}-2x-3}$$

Do the multiplications in x+4-2\left(x+1\right).

$$\frac{x+4-2x-2}{\left(x-1\right)\left(x+1\right)\left(x+4\right)}+\frac{1}{x^{2}-2x-3}$$

Combine like terms in x+4-2x-2.

$$\frac{-x+2}{\left(x-1\right)\left(x+1\right)\left(x+4\right)}+\frac{1}{x^{2}-2x-3}$$

Factor x^{2}-2x-3.

$$\frac{-x+2}{\left(x-1\right)\left(x+1\right)\left(x+4\right)}+\frac{1}{\left(x-3\right)\left(x+1\right)}$$

To add or subtract expressions, expand them to make their denominators the same. Least common multiple of \left(x-1\right)\left(x+1\right)\left(x+4\right) and \left(x-3\right)\left(x+1\right) is \left(x-3\right)\left(x-1\right)\left(x+1\right)\left(x+4\right). Multiply \frac{-x+2}{\left(x-1\right)\left(x+1\right)\left(x+4\right)} times \frac{x-3}{x-3}. Multiply \frac{1}{\left(x-3\right)\left(x+1\right)} times \frac{\left(x-1\right)\left(x+4\right)}{\left(x-1\right)\left(x+4\right)}.

$$\frac{\left(-x+2\right)\left(x-3\right)}{\left(x-3\right)\left(x-1\right)\left(x+1\right)\left(x+4\right)}+\frac{\left(x-1\right)\left(x+4\right)}{\left(x-3\right)\left(x-1\right)\left(x+1\right)\left(x+4\right)}$$

Since \frac{\left(-x+2\right)\left(x-3\right)}{\left(x-3\right)\left(x-1\right)\left(x+1\right)\left(x+4\right)} and \frac{\left(x-1\right)\left(x+4\right)}{\left(x-3\right)\left(x-1\right)\left(x+1\right)\left(x+4\right)} have the same denominator, add them by adding their numerators.

$$\frac{\left(-x+2\right)\left(x-3\right)+\left(x-1\right)\left(x+4\right)}{\left(x-3\right)\left(x-1\right)\left(x+1\right)\left(x+4\right)}$$

Do the multiplications in \left(-x+2\right)\left(x-3\right)+\left(x-1\right)\left(x+4\right).

$$\frac{-x^{2}+3x+2x-6+x^{2}+4x-x-4}{\left(x-3\right)\left(x-1\right)\left(x+1\right)\left(x+4\right)}$$

Combine like terms in -x^{2}+3x+2x-6+x^{2}+4x-x-4.

$$\frac{8x-10}{\left(x-3\right)\left(x-1\right)\left(x+1\right)\left(x+4\right)}$$

Expand \left(x-3\right)\left(x-1\right)\left(x+1\right)\left(x+4\right).

$$\frac{8x-10}{x^{4}+x^{3}-13x^{2}-x+12}$$

Differentiate w.r.t. x

$$\frac{2\left(43-130x+67x^{2}+12x^{3}-12x^{4}\right)}{\left(\left(x-3\right)\left(x+4\right)\left(x^{2}-1\right)\right)^{2}}$$