Suppose you have n items from which you choose r at a time. Explain why you must divide the number of permutations n!(n−r)! fraction n factorial , over open n minus r close factorial end fraction by r! to find the number of combinations n!r!(n−r)!.

Need ! give step by step solutions on how to solve number one [tex]\frac{9-2\sqrt{3} }{12+\sqrt{3} }[/tex] number two [tex]x+4=\sqrt{13x-20}[/tex] number three (domain and range) [tex]f(x)=2\sqrt[3]{x} +1[/tex]

Complete the equation of the line through (−10,3) and (−8,−8). use exact numbers.

Angle xyz is formed by segments xy and yz on the coordinate grid below: a coordinate plane is shown. angle xyz has endpoints at 3 comma negative 1 and 6 negative 2 and 3 comma negative 3 and measures 36.87 degrees. angle xyz is rotated 270 degrees counterclockwise about the origin to form angle x′y′z′. which statement shows the measure of angle x′y′z′?