Solve x/x-1div9/x+8

$$\frac { x } { x - 1 } \div \frac { 9 } { x + 8 }$$

Evaluate

$$\frac{x\left(x+8\right)}{9\left(x-1\right)}$$

Short Solution Steps

Divide \frac{x}{x-1} by \frac{9}{x+8} by multiplying \frac{x}{x-1} by the reciprocal of \frac{9}{x+8}.

$$\frac{x\left(x+8\right)}{\left(x-1\right)\times 9}$$

Use the distributive property to multiply x by x+8.

$$\frac{x^{2}+8x}{\left(x-1\right)\times 9}$$

Use the distributive property to multiply x-1 by 9.

$$\frac{x^{2}+8x}{9x-9}$$

Differentiate w.r.t. x

$$\frac{\left(x-4\right)\left(x+2\right)}{9\left(x-1\right)^{2}}$$

Steps Using Derivative Rule for Quotient

Divide \frac{x}{x-1} by \frac{9}{x+8} by multiplying \frac{x}{x-1} by the reciprocal of \frac{9}{x+8}.

$$\frac{\mathrm{d}}{\mathrm{d}x}(\frac{x\left(x+8\right)}{\left(x-1\right)\times 9})$$

Use the distributive property to multiply x by x+8.

$$\frac{\mathrm{d}}{\mathrm{d}x}(\frac{x^{2}+8x}{\left(x-1\right)\times 9})$$

Use the distributive property to multiply x-1 by 9.

$$\frac{\mathrm{d}}{\mathrm{d}x}(\frac{x^{2}+8x}{9x-9})$$

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.

$$\frac{\left(9x^{1}-9\right)\frac{\mathrm{d}}{\mathrm{d}x}(x^{2}+8x^{1})-\left(x^{2}+8x^{1}\right)\frac{\mathrm{d}}{\mathrm{d}x}(9x^{1}-9)}{\left(9x^{1}-9\right)^{2}}$$

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}.

$$\frac{\left(9x^{1}-9\right)\left(2x^{2-1}+8x^{1-1}\right)-\left(x^{2}+8x^{1}\right)\times 9x^{1-1}}{\left(9x^{1}-9\right)^{2}}$$

Simplify.

$$\frac{\left(9x^{1}-9\right)\left(2x^{1}+8x^{0}\right)-\left(x^{2}+8x^{1}\right)\times 9x^{0}}{\left(9x^{1}-9\right)^{2}}$$

Multiply 9x^{1}-9 times 2x^{1}+8x^{0}.

$$\frac{9x^{1}\times 2x^{1}+9x^{1}\times 8x^{0}-9\times 2x^{1}-9\times 8x^{0}-\left(x^{2}+8x^{1}\right)\times 9x^{0}}{\left(9x^{1}-9\right)^{2}}$$

Multiply x^{2}+8x^{1} times 9x^{0}.

$$\frac{9x^{1}\times 2x^{1}+9x^{1}\times 8x^{0}-9\times 2x^{1}-9\times 8x^{0}-\left(x^{2}\times 9x^{0}+8x^{1}\times 9x^{0}\right)}{\left(9x^{1}-9\right)^{2}}$$

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

$$\frac{9\times 2x^{1+1}+9\times 8x^{1}-9\times 2x^{1}-9\times 8x^{0}-\left(9x^{2}+8\times 9x^{1}\right)}{\left(9x^{1}-9\right)^{2}}$$

Simplify.

$$\frac{18x^{2}+72x^{1}-18x^{1}-72x^{0}-\left(9x^{2}+72x^{1}\right)}{\left(9x^{1}-9\right)^{2}}$$

Combine like terms.

$$\frac{9x^{2}-18x^{1}-72x^{0}}{\left(9x^{1}-9\right)^{2}}$$

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

$$\frac{9x^{2}-18x-72x^{0}}{\left(9x-9\right)^{2}}$$

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

$$\frac{9x^{2}-18x-72}{\left(9x-9\right)^{2}}$$