1.Relation and Function
hard

माना $3$ घात का एक बहुपद $f ( x )$ इस प्रकार है कि $K =2,3,4,5$ के लिए $f( k )=-\frac{2}{ k }$ है। तब $52-10 f(10)$ का मान के बराबर है ........ |

A

$26$

B

$36$

C

$52$

D

$87$

(JEE MAIN-2021)

Solution

$\mathrm{k}\, \mathrm{f}(\mathrm{k})+2=\lambda(\mathrm{x}-2)(\mathrm{x}-3)(\mathrm{x}-4)(\mathrm{x}-5) \ldots(1)$

put $\mathrm{x}=0$

we get $\lambda=\frac{1}{60}$

Now put $\lambda$ in equation $(1)$

$\Rightarrow \mathrm{k\,f}(\mathrm{k})+2=\frac{1}{60}(\mathrm{x}-2)(\mathrm{x}-3)(\mathrm{x}-4)(\mathrm{x}-5)$

Put $\mathrm{x}=10$

$\Rightarrow 10 \,\mathrm{f}(10)+2=\frac{1}{60}(8)(7)(6)(5)$

$\Rightarrow 52-10 \,\mathrm{f}(10)=52-26=26$

Standard 12
Mathematics

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