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

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 Multiple Choice QuestionsMultiple Choice Questions

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1.

The sum of coefficients of integral powers of x in the binomial expansion of left parenthesis 1 minus 2 square root of straight x right parenthesis to the power of 50 space is

  • 1 half left parenthesis 3 to the power of 50 space plus space 1 right parenthesis
  • 1 half left parenthesis 30 to the power of 50 right parenthesis
  • 1 half left parenthesis 30 to the power of 50 minus 1 right parenthesis
  • 1 half left parenthesis 30 to the power of 50 minus 1 right parenthesis


A.

1 half left parenthesis 3 to the power of 50 space plus space 1 right parenthesis

Let Tr+1 be the general term in the expansion of left parenthesis 1 minus 2 square root of straight x right parenthesis to the power of 60

therefore space straight T subscript straight r plus 1 end subscript space equals space straight C presuperscript 50 subscript straight r space left parenthesis 1 right parenthesis to the power of 50 minus straight r end exponent left parenthesis negative 2 straight x to the power of 1 divided by 2 end exponent right parenthesis to the power of straight r space equals space straight C presuperscript 50 subscript straight r 2 to the power of straight r straight x to the power of straight r divided by 2 end exponent left parenthesis negative 1 right parenthesis to the power of straight r
For the integral power of x, r should be even integer,
therefore, sum of coefficients= 

sum from straight r space equals 0 to 25 of space to the power of 50 straight C subscript 2 straight r end subscript space left parenthesis 2 right parenthesis to the power of 2 straight r end exponent
space equals space 1 half left parenthesis 1 plus 2 right parenthesis to the power of 50 space plus space left parenthesis 1 minus 2 right parenthesis to the power of 50 right square bracket
space equals space 1 half left square bracket 3 to the power of 50 plus 1 right square bracket

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2.

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

192 Views

3.

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

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4.

The term independent of  x in open parentheses fraction numerator straight x plus 1 over denominator straight x to the power of 2 divided by 3 end exponent minus straight x to the power of 1 divided by 3 end exponent space plus 1 end fraction minus fraction numerator straight x minus 1 over denominator straight x minus straight x to the power of 1 divided by 2 end exponent end fraction close parentheses to the power of 10 is 

  • 4

  • 120

  • 18

  • 18

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5.

If n is a positive integer, then open parentheses square root of 3 plus 1 close parentheses to the power of 2 straight n end exponent minus space left parenthesis square root of 3 minus 1 right parenthesis to the power of 2 straight n end exponent space is

  • an irrational number

  • an odd positive integer

  • an even positive integer

  • an even positive integer

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6.

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

  • 144

  • -132

  • -144

  • -144

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7.

The value of
(21C110C1) + (21C210C2) + (21C310C3) + (21C410C4) + .... +
(21C1010C10) is

  • 220 – 210

  • 221 – 211

  • 221 – 210

  • 221 – 210

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8. Statement space minus 1 space colon space sum from straight r space equals space 0 to straight n of space left parenthesis straight r plus 1 right parenthesis space to the power of straight n straight C subscript straight r space equals space left parenthesis straight n plus 2 right parenthesis 2 to the power of straight n minus 1 end exponent
Statement space minus space 2 colon thin space sum from straight r equals 0 to straight n of space left parenthesis straight r plus 1 right parenthesis space to the power of straight n straight C subscript straight r straight x to the power of straight r space equals space left parenthesis 1 plus straight x right parenthesis to the power of straight n space plus space nx space left parenthesis 1 plus straight x right parenthesis to the power of straight n minus 1 end exponent
  • Statement −1 is false, Statement −2 is true

  • Statement −1 is true, Statement −2 is true, Statement −2 is a correct explanation for Statement −1

  • Statement −1 is true, Statement −2 is true; Statement −2 is not a correct explanation for Statement −1.

  • Statement −1 is true, Statement −2 is true; Statement −2 is not a correct explanation for Statement −1.

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9.

In the binomial expansion of (a - b)n, n ≥ 5, the sum of 5th and 6th terms is zero, then
a/b equals

  • 5/n −4

  • 6 /n −5

  • n -5 /6

  • n -5 /6

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10.

The sum of the series 20C020C1 + 20C220C3 + …… - ….. + 20C10 is-

  • 20C10

  • 1 half straight C presuperscript 20 subscript 10
  • 0

  • 0

1417 Views

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