Solve 5x/x^2-7x-4/2x-14+9/x

$$\frac{ 5x }{ { x }^{ 2 } -7x } - \frac{ 4 }{ 2x-14 } + \frac{ 9 }{ x }$$

Evaluate

$$\frac{3\left(4x-21\right)}{x\left(x-7\right)}$$

Short Solution Steps

Factor the expressions that are not already factored in \frac{5x}{x^{2}-7x}.

$$\frac{5x}{x\left(x-7\right)}-\frac{4}{2x-14}+\frac{9}{x}$$

Cancel out x in both numerator and denominator.

$$\frac{5}{x-7}-\frac{4}{2x-14}+\frac{9}{x}$$

Factor 2x-14.

$$\frac{5}{x-7}-\frac{4}{2\left(x-7\right)}+\frac{9}{x}$$

To add or subtract expressions, expand them to make their denominators the same. Least common multiple of x-7 and 2\left(x-7\right) is 2\left(x-7\right). Multiply \frac{5}{x-7} times \frac{2}{2}.

$$\frac{5\times 2}{2\left(x-7\right)}-\frac{4}{2\left(x-7\right)}+\frac{9}{x}$$

Since \frac{5\times 2}{2\left(x-7\right)} and \frac{4}{2\left(x-7\right)} have the same denominator, subtract them by subtracting their numerators.

$$\frac{5\times 2-4}{2\left(x-7\right)}+\frac{9}{x}$$

Do the multiplications in 5\times 2-4.

$$\frac{10-4}{2\left(x-7\right)}+\frac{9}{x}$$

Do the calculations in 10-4.

$$\frac{6}{2\left(x-7\right)}+\frac{9}{x}$$

To add or subtract expressions, expand them to make their denominators the same. Least common multiple of 2\left(x-7\right) and x is 2x\left(x-7\right). Multiply \frac{6}{2\left(x-7\right)} times \frac{x}{x}. Multiply \frac{9}{x} times \frac{2\left(x-7\right)}{2\left(x-7\right)}.

$$\frac{6x}{2x\left(x-7\right)}+\frac{9\times 2\left(x-7\right)}{2x\left(x-7\right)}$$

Since \frac{6x}{2x\left(x-7\right)} and \frac{9\times 2\left(x-7\right)}{2x\left(x-7\right)} have the same denominator, add them by adding their numerators.

$$\frac{6x+9\times 2\left(x-7\right)}{2x\left(x-7\right)}$$

Do the multiplications in 6x+9\times 2\left(x-7\right).

$$\frac{6x+18x-126}{2x\left(x-7\right)}$$

Combine like terms in 6x+18x-126.

$$\frac{24x-126}{2x\left(x-7\right)}$$

Factor the expressions that are not already factored in \frac{24x-126}{2x\left(x-7\right)}.

$$\frac{6\left(4x-21\right)}{2x\left(x-7\right)}$$

Cancel out 2 in both numerator and denominator.

$$\frac{3\left(4x-21\right)}{x\left(x-7\right)}$$

Expand x\left(x-7\right).

$$\frac{3\left(4x-21\right)}{x^{2}-7x}$$

Use the distributive property to multiply 3 by 4x-21.

$$\frac{12x-63}{x^{2}-7x}$$

Differentiate w.r.t. x

$$\frac{3\left(-4x^{2}+42x-147\right)}{\left(x\left(x-7\right)\right)^{2}}$$

Steps Using Derivative Rule for Quotient

Factor the expressions that are not already factored in \frac{5x}{x^{2}-7x}.

$$\frac{\mathrm{d}}{\mathrm{d}x}(\frac{5x}{x\left(x-7\right)}-\frac{4}{2x-14}+\frac{9}{x})$$

Cancel out x in both numerator and denominator.

$$\frac{\mathrm{d}}{\mathrm{d}x}(\frac{5}{x-7}-\frac{4}{2x-14}+\frac{9}{x})$$

Factor 2x-14.

$$\frac{\mathrm{d}}{\mathrm{d}x}(\frac{5}{x-7}-\frac{4}{2\left(x-7\right)}+\frac{9}{x})$$

To add or subtract expressions, expand them to make their denominators the same. Least common multiple of x-7 and 2\left(x-7\right) is 2\left(x-7\right). Multiply \frac{5}{x-7} times \frac{2}{2}.

$$\frac{\mathrm{d}}{\mathrm{d}x}(\frac{5\times 2}{2\left(x-7\right)}-\frac{4}{2\left(x-7\right)}+\frac{9}{x})$$

Since \frac{5\times 2}{2\left(x-7\right)} and \frac{4}{2\left(x-7\right)} have the same denominator, subtract them by subtracting their numerators.

$$\frac{\mathrm{d}}{\mathrm{d}x}(\frac{5\times 2-4}{2\left(x-7\right)}+\frac{9}{x})$$

Do the multiplications in 5\times 2-4.

$$\frac{\mathrm{d}}{\mathrm{d}x}(\frac{10-4}{2\left(x-7\right)}+\frac{9}{x})$$

Do the calculations in 10-4.

$$\frac{\mathrm{d}}{\mathrm{d}x}(\frac{6}{2\left(x-7\right)}+\frac{9}{x})$$

To add or subtract expressions, expand them to make their denominators the same. Least common multiple of 2\left(x-7\right) and x is 2x\left(x-7\right). Multiply \frac{6}{2\left(x-7\right)} times \frac{x}{x}. Multiply \frac{9}{x} times \frac{2\left(x-7\right)}{2\left(x-7\right)}.

$$\frac{\mathrm{d}}{\mathrm{d}x}(\frac{6x}{2x\left(x-7\right)}+\frac{9\times 2\left(x-7\right)}{2x\left(x-7\right)})$$

Since \frac{6x}{2x\left(x-7\right)} and \frac{9\times 2\left(x-7\right)}{2x\left(x-7\right)} have the same denominator, add them by adding their numerators.

$$\frac{\mathrm{d}}{\mathrm{d}x}(\frac{6x+9\times 2\left(x-7\right)}{2x\left(x-7\right)})$$

Do the multiplications in 6x+9\times 2\left(x-7\right).

$$\frac{\mathrm{d}}{\mathrm{d}x}(\frac{6x+18x-126}{2x\left(x-7\right)})$$

Combine like terms in 6x+18x-126.

$$\frac{\mathrm{d}}{\mathrm{d}x}(\frac{24x-126}{2x\left(x-7\right)})$$

Factor the expressions that are not already factored in \frac{24x-126}{2x\left(x-7\right)}.

$$\frac{\mathrm{d}}{\mathrm{d}x}(\frac{6\left(4x-21\right)}{2x\left(x-7\right)})$$

Cancel out 2 in both numerator and denominator.

$$\frac{\mathrm{d}}{\mathrm{d}x}(\frac{3\left(4x-21\right)}{x\left(x-7\right)})$$

Use the distributive property to multiply 3 by 4x-21.

$$\frac{\mathrm{d}}{\mathrm{d}x}(\frac{12x-63}{x\left(x-7\right)})$$

Use the distributive property to multiply x by x-7.

$$\frac{\mathrm{d}}{\mathrm{d}x}(\frac{12x-63}{x^{2}-7x})$$

For any two differentiable functions, the derivative of the quotient of two functions is the denominator times the derivative of the numerator minus the numerator times the derivative of the denominator, all divided by the denominator squared.

$$\frac{\left(x^{2}-7x^{1}\right)\frac{\mathrm{d}}{\mathrm{d}x}(12x^{1}-63)-\left(12x^{1}-63\right)\frac{\mathrm{d}}{\mathrm{d}x}(x^{2}-7x^{1})}{\left(x^{2}-7x^{1}\right)^{2}}$$

The derivative of a polynomial is the sum of the derivatives of its terms. The derivative of a constant term is 0. The derivative of ax^{n} is nax^{n-1}.

$$\frac{\left(x^{2}-7x^{1}\right)\times 12x^{1-1}-\left(12x^{1}-63\right)\left(2x^{2-1}-7x^{1-1}\right)}{\left(x^{2}-7x^{1}\right)^{2}}$$

Simplify.

$$\frac{\left(x^{2}-7x^{1}\right)\times 12x^{0}-\left(12x^{1}-63\right)\left(2x^{1}-7x^{0}\right)}{\left(x^{2}-7x^{1}\right)^{2}}$$

Multiply x^{2}-7x^{1} times 12x^{0}.

$$\frac{x^{2}\times 12x^{0}-7x^{1}\times 12x^{0}-\left(12x^{1}-63\right)\left(2x^{1}-7x^{0}\right)}{\left(x^{2}-7x^{1}\right)^{2}}$$

Multiply 12x^{1}-63 times 2x^{1}-7x^{0}.

$$\frac{x^{2}\times 12x^{0}-7x^{1}\times 12x^{0}-\left(12x^{1}\times 2x^{1}+12x^{1}\left(-7\right)x^{0}-63\times 2x^{1}-63\left(-7\right)x^{0}\right)}{\left(x^{2}-7x^{1}\right)^{2}}$$

To multiply powers of the same base, add their exponents.

$$\frac{12x^{2}-7\times 12x^{1}-\left(12\times 2x^{1+1}+12\left(-7\right)x^{1}-63\times 2x^{1}-63\left(-7\right)x^{0}\right)}{\left(x^{2}-7x^{1}\right)^{2}}$$

Simplify.

$$\frac{12x^{2}-84x^{1}-\left(24x^{2}-84x^{1}-126x^{1}+441x^{0}\right)}{\left(x^{2}-7x^{1}\right)^{2}}$$

Combine like terms.

$$\frac{-12x^{2}+126x^{1}-441x^{0}}{\left(x^{2}-7x^{1}\right)^{2}}$$

For any term t, t^{1}=t.

$$\frac{-12x^{2}+126x-441x^{0}}{\left(x^{2}-7x\right)^{2}}$$

For any term t except 0, t^{0}=1.

$$\frac{-12x^{2}+126x-441}{\left(x^{2}-7x\right)^{2}}$$