KVPY2020MathematicsBinomial Theorem
Let r be the remainder when 2021 2020 is divided by 2020 2 . Then r lies between
Options
- A0 and 5
- B10 and 15
- C20 and 100
- D107 and 120
Correct answer
A. 0 and 5
Step-by-step solution
( 2021 ) 2020 = ( 1 + 2020 ) 2020 C 0 2020 + C 1 2020 · 2020 + C 2 2020 · 2020 2 + … + C 2020 2020 · 2020 2020 1 + 2020 2 + C 2 2020 · 2020 2 + … + C 2020 2020 · 2020 2020 1 + 2020 2 1 + C 2 2020 + … + 2020 2018 1 + ( 2020 ) 2 · λ Hence ( 2021 ) 2020 = λ ( 2020 ) 2 + 1 Hence remainder = 1