Cho A=1/1+3+1/1+3+5+1/1+3+5+7+……+1/1+3+5+7+…….+2021 Chứng minh rằng A nhỏ hơn 3/ 4 26/07/2021 Bởi Reagan Cho A=1/1+3+1/1+3+5+1/1+3+5+7+……+1/1+3+5+7+…….+2021 Chứng minh rằng A nhỏ hơn 3/ 4
A=1/1+3+1/1+3+5+...........+1/1+3+.....+2013 A=1(1+3).2/2+1(1+5).3/2+.........+1/(1+2013).1007/2 A=2/2.4+23.6+2/4.8+...........+2/1007.2014 A=1/2.2+1/3.3+1/4.4+..........+1/1007.1007 ⇒A<1/2.2+(1/2.3+1/3.4+......+1/1006.1008) ⇒A<1/4+(1/2−1/3+1/3−1/4+...........+1/1006−1/1007) ⇒A<1/4+(1/2−1/1007) ⇒A<1/4+1/2=3/4⇒A<1/4+1/2=3/4 →đpcm. Xin hay nhất.. Bình luận
A=1/1+3+1/1+3+5+...........+1/1+3+.....+2013
A=1(1+3).2/2+1(1+5).3/2+.........+1/(1+2013).1007/2
A=2/2.4+23.6+2/4.8+...........+2/1007.2014
A=1/2.2+1/3.3+1/4.4+..........+1/1007.1007
⇒A<1/2.2+(1/2.3+1/3.4+......+1/1006.1008)
⇒A<1/4+(1/2−1/3+1/3−1/4+...........+1/1006−1/1007)
⇒A<1/4+(1/2−1/1007)
⇒A<1/4+1/2=3/4⇒A<1/4+1/2=3/4 →đpcm. Xin hay nhất..