Răspuns:
22.(n+2)!/n!=12
n!(n+1)(n+2)/n!=12
(n+1)(n+2)=3*4=>
n+1=3
n+2=4=>
n=2
25)Cₙ⁰+Cₙ¹=2012
1+n=2012
n=2011
27)(2x+∛x)¹⁰=
(2x+x^1/3)¹⁰
Tₙ₊₁=T₆=>
n+1=6
n=5
T₆=C₁₀⁶(2x)⁶*(x^1/3)¹⁰⁻⁶=
10!/6!*(6-4)!*2⁶*x⁶(x^1/3)⁴=
7*8*9*10/2!*64*x⁶*x^4/3=
7*8*9*5*64x^(6+4/3)=
56*45*64*x^22/3=
161280x^22/3
Explicație pas cu pas:
