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Question Number 113710 by mr W last updated on 14/Sep/20

y o u h a v e 2 i d e n t i c a l m a t h e m a t i c s

b o o k s, 2 i d e n t i c a l p h y s i c s b o o k s, 2

i d e n t i c a l c h e m i s t r y b o o k s, 2 i d e n t i c a l

b i o l o g y b o o k s a n d 2 g e o g r a p h y b o o k s .

i n h o w m a n y w a y s c a n y o u c o m p i l e

t h e s e b o o k s s u c h t h a t s a m e b o o k s

a r e n o t m u t u a l l y a d j a c e n t ?

Commented by I want to learn more last updated on 16/Sep/20

Great sir,

But does this method solve your previous question ?

Q 112934

Commented by mr W last updated on 16/Sep/20

n o

Answered by mr W last updated on 15/Sep/20

\frac{10!}{2^{5}} - C_{1}^{5} \times \frac{9!}{2^{4}} + C_{2}^{5} \times \frac{8!}{2^{3}} - C_{3}^{5} \times \frac{7!}{2^{2}} + C_{4}^{5} \times \frac{6!}{2} - 5!

= 39480

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