How do you simplify this expression

For the first one multiply X by X-5 = x^2-5x. X^2+x^2 -5x-X +7. 2x^2-6x+7. For the second one use FOIL: multiply the first terms in each parentheses (X times X) then the outside ones (X times -7) then inside (5 times X) then the last two (5 times -7) x^2-7x+5x-35 combine like terms x^2-2x-35 :)

Population: The entire number of students present in town's high school.

Sample: Identical number of students across various categories of fresher's, senior students & juniors.

Population is the large set of the people who are present during the experiment. Sample is a smaller subset from the experiment. In this question, samples are the students who are either new joiners to the college, the senior students or the juniors. It will help Alan to come to a possible conclusion using the survey.