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If `x in R ,`the numbers `2^(1+x)+2^(1-x), b//2,36^x+36^(-x)`form an A.P., then `b`may lie in theinterval`[12 ,oo)`b. `[6,oo)`c. `(-oo,6]`d. `[6, 12]`A. `[12, oo)`B. `[6, oo)`C. `(-oo, 6]`D. `[6, 12]` |
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Answer» Correct Answer - B If `x in R`, the numbers …………. `b = (2^(t+x)+2^(t-x))+(36^(x)+36^(-x))` ` = 2underset(ge2)underbrace((2^(x)+2^(-x))) + underset(ge2)underbrace((6^(2x)+6^(-2x)))` `implies b ge 2(2)+2 = 6` `i.e. b in [6, oo)` |
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