KVPY2016MathematicsBinomial Theorem
The number of all 2 -digit numbers n such that n is equal to the sum of the square of digit in its tens place and the cube of the digit in units place is
Options
- A0
- B1
- C2
- D4
Correct answer
C. 2
Step-by-step solution
n = ab ab = a ²+ b ³ 10 a + b = a ²+ b ³ a (10- a )+ b (1- b )(1+ b )=0 a (10- a )=( b -1)( b )( b +1) If b =2 ; a (10- a )=6 no value of ^ a ^ b =3 ; a (10- a )=24 a 4,6 nos. are 43 & 63 b =4 ; a (10- a )=60 no value of a b =5 ; a (10- a )=120 no need to check further nos. are 43 & 63 .