171. The coefficients of the (r - 1)^th, r^th and (r + 1)^th terms in the expansion of (x + 1)ⁿ are in the ratio 1 : 3 : 5. Find n and r. 

Find the absolute term in the expansion of: 

The sum of coefficients of integral powers of x in the binomial expansion of  is

If (10)⁹ +2 (11)²(10)⁷ + .....+10 (11)⁹ = K(10)⁹, then k is equal to

• 121/10

• 441/100

• 100

• 100

A multiple choice examination has 5 questions. Each question has three alternative answers of which exactly one is correct. The probability that a student will get 4 or more correct answers just by guessing is

• 17/3⁵

• 13/3⁵

• 11/3⁵

• 11/3⁵

The term independent of  x in  is 

• 4

• 120

• 18

• 18

If n is a positive integer, then  is

• an irrational number

• an odd positive integer

• an even positive integer

• an even positive integer

The coefficient of x⁷ in the expansion of (1 - x - x² +x³)⁶ is :

• 144

• -132

• -144

• -144

The value of
(²¹C₁ – ¹⁰C₁) + (²¹C₂ – ¹⁰C₂) + (²¹C₃ – ¹⁰C₃) + (²¹C₄ – ¹⁰C₄) + .... +
(²¹C₁₀ – ¹⁰C₁₀) is

• 2²⁰ – 2¹⁰

• 2²¹ – 2¹¹

• 2²¹ – 2¹⁰

• 2²¹ – 2¹⁰