The average of a positive number, its square and 3 is 5. Find the number.
Answer & explanation
Correct answer: option 2
Assume the number be n.
Square of the number = n2
Average of n, n2 and 3 = (3+n+n2)/3 = 5
3+n+n2 = 15
n2 + n -12 = 0
n2 + 4n - 3n -12 = 0
(n+4)(n-3)=0
The correct answer is Option (2) → 3