Question

se considera numarul a=2supra1*3+2supra3*5...2supra49*51. stabiliti daca a apartine de (1supra2;1)

Answer 1

2/1*3= 1/1-1/3
2/3*5=1/3-1/5
2/5*7=1/5-1/7
...................
2/49*51=1/49-1/51
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2/1*3+2/3*5 +....+2/49*51 =(1/1-1/3) +(1/3-1/5)+(1/5-1/7)+...+(1/49-1/51)
                                        =1/1 -1/51 =50/51 
cum 51/102 =1/2 <100/102 < 102/102=1 => 50/51 apartine (1/2,1)