JEE Main202225 Jun 2022Evening ShiftMathematicsBinomial TheoremActual
The coefficient of x 101 in the expression 5 + x 500 + x 5 + x 499 + x 2 5 + x 498 + … … + x 500 , x > 0 is
Options
- A  501 C 101 × 5 399
- B  501 C 101 × 5 400
- C  501 C 100 × 5 400
- D500 C 101 × 5 399
Correct answer
A.   501 C 101 × 5 399
Step-by-step solution
Given, 5 + x 500 + x 5 + x 499 + x 2 5 + x 498 + … … + x 500 Using sum of the G.P in the given expression we get, ⇒ 5 + x 500 x 5 + x 501 - 1 x 5 + x - 1 = x 501 - 5 + x 501 - 5 = 1 5 5 + x 501 - x 501 5 Now coefficient of x 101 in 1 5 5 + x 501 will be 1 5 C 101 501 5 501 - 101 = 5 399 C 101 501