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Q.4.     If \frac{1}{6!}+\frac{1}{7!}=\frac{x}{8!}, find x

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best_answer

Factorial can be given as : 

To find x  : \frac{1}{6!}+\frac{1}{7!}=\frac{x}{8!},

 R.H.S :\, \, \frac{1}{6!}+\frac{1}{7!}

= \frac{1}{6!}+\frac{1}{7\times 6!}

= \frac{1}{6!}(1+\frac{1}{7})

= \frac{1}{6!}(\frac{8}{7})

L.H.S:\, \, \frac{x}{8!},

                =\frac{x}{8\times 7\times 6!}

 Given :     L.H.S= R.H.S

        \frac{1}{6!}\left ( \frac{8}{7} \right )=\frac{x}{8\times 7\times 6!}

              \Rightarrow \, \, 8=\frac{x}{8}

               \Rightarrow \, \, x=8\times 8=64

 

 

 

 

Posted by

seema garhwal

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