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If `p=(8+3sqrt(7))^n a n df=p-[p],w h e r e[dot]`denotes the greatest integer function, then the value of `p(1-f)`is equal to`1`b. `2`c. `2^n`d. `2^(2n)`A. 1B. 2C. `2^(n)`D. `2^(2n)` |
Answer» Correct Answer - A `p=(8+3sqrt(7))^(n)=.^(n)C_(0)8^(n)+.^(n)C_(1)8^(n-1)(3sqrt(7))+"...."` Let `p_(1)=(8-3sqrt(7))^(n)=.^(n)C_(0)8^(n)-.^(7)C_(1)8^(n-1)(3sqrt(7))+"....."` `p + p_(1) = 2(.^(n)C_(0)8^(n)+.^(n)C_(2)8^(n-2)(3sqrt(7))^(2)+".....")="even integer"` `p_(1)` clearly belongs to `(0,1)` `rArr [p] = f+p_(1) = "even integer"` `rArr f + p_(1) = "integer"` `f in (0,1),p_(1)in(0,1)` `rArr f + p in (0,2)` `rArr f+ p_(1) = 1` `rArr p_(1)=1-f` Now, `p(1-f)=pp_(1)=[(8+3sqrt(7))^(n)(8-3sqrt(7))]^(n)=1` |
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