Question

ex 3 si 4
dau coroana.............​

Answer 1

Răspuns:

Explicație pas cu pas:

Ex3. √3+arctgx=π/2, ⇒√3=π/2 -arctgx, ⇒ √3=arcctgx, ⇒ x=π/6.

Ex4

$C_{2n}^{n}=2*C_{2n-1}^{n}~=>~\dfrac{(2n)!}{n!*(2n-n)!} =2*\dfrac{(2n-1)!}{n!*(2n-1-n)!}~=>~\\\dfrac{(2n)!}{n!*n!}=\dfrac{2*(2n-1)!}{n!*(n-1)!}~=>~\dfrac{(2n)!}{2*(2n-1)!}=\dfrac{n!*n!}{n!*(n-1)!}~=>\\\dfrac{(2n-1)!*(2n)}{2*(2n-1)!}=\dfrac{n!*n!}{n!*(n-1)!}~=>n=\dfrac{(n-1)!*n}{(n-1)!}~=>~n=n.$

p.s. Imagine e pentru cazul când de pe telefon nu se citește ... Succese!