SOLUTION: If the pupil in a class sends a New Year greeting cards to every classmate ,the total number of cards sent out will be 870. Find the number of pupils in the class.

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equations Lessons -> SOLUTION: If the pupil in a class sends a New Year greeting cards to every classmate ,the total number of cards sent out will be 870. Find the number of pupils in the class.       Log On


   

Question 971960: If the pupil in a class sends a New Year greeting cards to every classmate ,the total number of cards sent out will be 870. Find the number of pupils in the class.
Answer by checkley77(12844) About Me  (Show Source):
You can put this solution on YOUR website!
EVERY PUPIL SENDS CARDS TO (X-1) PUPILS.
X IS THE TOTAL NUMBER OF PUPILS.
X(X-1)=870
X^2-X-870=0
(X-30)(X+29)=0
X-30=0
X=30 NUMBER OF PUPILS.