if nC2 -nC1=35 THEN FIND THE VALUE OF N ?

Dear Student,

Please find below the solution to the asked query:
C2n-C1n=35n!2!n-2!-n!1!n-1!=35nn-1n-2!2×n-2!-nn-1!n-1!=35nn-12-n=35n2-n-2n=70n2-3n-70=0n2+7n-10n-70=0nn+7-10n+7=0n+7n-10=0n=-7  or n=10n must be positive so n=10    Answer

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