Question

Va rog ajutați mă repede!!dau coroana!!​ 5 stele din inima cine răspunde repede

Answer 1

1. a= (1-1/2)(1-1/3)(1-1/4)…(1-1/50)
a= (2/2-1/2)(3/3-1/3)(4/4-1/4)…(50/50-1/50)
a=1/2*2/3*3/4*…*49/50 => a= 1*2*3*4*…*49/2*3*4*…*50= 1/50
b=(1+1/2)(1+1/3)(1+1/4)…(1+1/50)
b=(2/2+1/2)(3/3+1/3)(4/4+1/4)…(50/50+1/50)
b=3/2*4/3*5/4*…*51/50= 3*4*5*…*51/2*3*4*…*50 => b=51/2 b>a
2. pai a+b = (1/2+1/2)+(2/3+1/3)+…+(99/100+1/100) = 1 + 1 + 1 +…+1= 1*99=99
a+b/11=99/11=9