Question

Dau coroana si 28 de puncte.
Materie clasa a 10 a.
Multumesc anticipat​

Answer 1

Răspuns:

$\frac{n!}{8!(n-8)!}=\frac{n!}{10!(n-10)!}$

n!*10!(n-10)!=n!*8!(n-8)!=

10!(n-10)!=8!(n-8)!

9*10(n-10)!=(n-8)!

90(n-9)(n-10)=1

(90n-180)(n-10)=1

90n²-900n-180n+1800=1

90n²-1080n+1799=0

n1=$\frac{180-\sqrt{14410} }{30}$<10, nu convine

n2=$\frac{180+\sqrt{14410} }{30}$>10 convine