Given the arithmetic series 2 4 =420. find the first term a and the common difference d

Given the following statements, which is the best

How many sides does a regular polygon have if each exterior angle measure is 45 degrees explain your answer, i really don't understand this.

21 type the correct answer in the box. use numerals instead of words. if necessary, use / for the fraction bar. the solution set of n2 - 14n = -45 is { (separate the solutions with a comma)