91Ó°ÊÓ

Add or subtract as indicated. Simplify the result, if possible. $$\frac{9 x+3}{x^{2}-x-6}+\frac{x}{3-x}$$

Perform the indicated operation or operations. Simplify the result, if possible. $$\frac{b}{a c+a d-b c-b d}-\frac{a}{a c+a d-b c-b d}$$

Perform the indicated operation or operations. $$\frac{x^{2}+x z+x y+y z}{x-y} \div \frac{x+z}{x+y}$$

A company that manufactures wheelchairs has fixed costs of \(\$ 500,000 .\) The average cost per wheelchair, \(C,\) for the company to manufacture \(x\) wheelchairs per month is modeled by the formula $$ C=\frac{400 x+500,000}{x} $$ Use this mathematical model to solve Exercises \(69-70\). How many wheelchairs per month can be produced at an average cost of \(\$ 450\) per wheelchair?

A company that manufactures wheelchairs has fixed costs of \(\$ 500,000 .\) The average cost per wheelchair, \(C,\) for the company to manufacture \(x\) wheelchairs per month is modeled by the formula $$ C=\frac{400 x+500,000}{x} $$ Use this mathematical model to solve Exercises \(69-70\). How many wheelchairs per month can be produced at an average cost of \(\$ 405\) per wheelchair?

Perform the indicated operation or operations. Simplify the result, if possible. $$\frac{y}{a x+b x-a y-b y}-\frac{x}{a x+b x-a y-b y}$$

Add or subtract as indicated. Simplify the result, if possible. $$\frac{x^{2}+9 x}{x^{2}-2 x-3}+\frac{5}{3-x}$$

Perform the indicated operation or operations. $$\frac{x^{2}-x z+x y-y z}{x-y} \div \frac{x-z}{y-x}$$

Simplify each rational expression. If the rational expression cannot be simplified, so state. $$\frac{x^{2}-4}{2-x}$$

Factor completely: \(2 x^{3}-20 x^{2}+50 x\)