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If the function `f(x)=2x^3-9a x^2+12 x^2x+1,w h e r ea >0,`attains its maximum and minimum at `pa n dq`, respectively, such that `p^2=q ,`then `a`equal to1 (b) 2(c) `1/2`(d) 3A. 1B. 2C. `1/2`D. 3 |
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Answer» Correct Answer - 2 `f(x)=2x^(3)-9ax^(2)+12a^(2)x+1` `therefore f(X)=6x^(2)-18ax+12a^(2)and f(x)=12x-18a` For maximum /minimum , `6x^(2)-18ax+12a^(2)=0` or `x^(2)-3ax+2a^(2)=0` or `(x-a)(x-2a)=0` i.e x=a or x =2a Now `f'(a)=12a=18a=6alt0` Therefore f(X) is maximum at x=a and minimum at x=2a Thus p=a and q =2a Given that `p^(2) = q or a^(2)=2a or a (a-2) =0 or a=2` |
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