Question

A College runs 25 classes on Monday. Ten of the classes have an average size of 12
students while the other fifteen classes have an average size of 12.2 students. What is
the average class size, in students, of all 25 classes run on Monday?
12.5
013
13.2
O 13.5
O 14​

Answer 1

Answer:

This implies that

x2+2ax=4x−4a−13

or

x2+2ax−4x+4a+13=0

or

x2+(2a−4)x+(4a+13)=0

Since the equation has just one solution instead of the usual two distinct solutions, then the two solutions must be same i.e. discriminant = 0.

Hence we get that

(2a−4)2=4⋅1⋅(4a+13)

or

4a2−16a+16=16a+52

or

4a2−32a−36=0

or

a2−8a−9=0

or

(a−9)(a+1)=0

So the values of a are −1 and 9.