Question

1)daca x reprezinta un an din Secolul XXsi x-1/2010=333/335 .x=?                                                                                        2)fie S=1/20+1/21+1/22+......+1/29 stiti cati termeni are suma? demonstrati ca 1/3<S<2/3

Answer 1

x=333*2019supra 335=669330:335=1998

Answer 2

(x - 1)/2010 = 333/335    x-1 = 2010·333/335 = 1998  x = 1999
2) 29-20+1 = 10 termeni
1/29 < 1/20    !/28 <1/20 ...........1/21 < 1/20 ⇒ S < 10·1/20    S < 1/2  ⇒ S < 2/3
1/20 > 1/21 > 1/22 > 1/23 >.........>1/29    S > 10·1/29    S > 10 /29    S >10/30  S >1/3