Iam not good at algebra so i really need with the problem 8n+4n^2-8n!

Prove that quadrilateral is a rhombus.

Atriangle has a side lengths of 18cm, 80 cm and 81cm. classify it as acute obtuse or right?

Suppose you are choosing a 6-digit personal access code. this code is made up of 4 digits chosen from 1 to 9, followed by 2 letters chosen from a to z. any of these digits or letters can be repeated. find the total number of personal access codes that can be formed. 492,804 341,172 39,917,124 4,435,236