Factorials !!!

Algebra Level 1

19 ! + 21 ! 20 ! \huge{\frac{19!+21!}{20!}} Find the value of above expression

This problem is a part of the set Easy Factorials

20.05 20.15 21.05 22.15

A Former Brilliant Member by A Former Brilliant Member

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4 solutions

5 Helpful 0 Interesting 0 Brilliant 0 Confused
Aryan Gaikwad
Apr 1, 2015

19 ! + 21 ! 20 ! = 19 ! ( 1 + 20 ⋅ 21 ) 20 ! = 1 + 420 20 = 21.05 \frac { 19!+21! }{ 20! } \\ =\frac { 19!(1+20\cdot 21) }{ 20! } \\ =\frac { 1+420 }{ 20 } \\ =21.05

2 Helpful 0 Interesting 0 Brilliant 0 Confused
Ashish Menon
Jul 30, 2016

19 ! + 21 ! 20 ! = 19 ! ( 1 + 21 × 20 ) 19 ! × 20 = 421 20 = 21.05 \begin{aligned} \dfrac{19! + 21!}{20!} & = \dfrac{19!(1 + 21×20)}{19! × 20}\\ \\ & = \dfrac{421}{20}\\ \\ & = \color{#3D99F6}{\boxed{21.05}} \end{aligned}

0 Helpful 0 Interesting 0 Brilliant 0 Confused

(19!+21!)= 19!(1+(20*21))=19!(421) (19!(421)/20!)= 421/20= 21.05

0 Helpful 0 Interesting 0 Brilliant 0 Confused

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