tính nhanh
1/2x3 + 1/3x4 + 1/4x5 + 1/5x6 + 1/6x7
1/2x3 + 1/3x4 + 1/4x5 + 1/5x6 + 1/6x7 + 1/20x21
A = 1/2x3 + 1/3x4 + 1/4x5 + 1/5x6 + 1/6x7 + 1/7x8
1/1x2 + 1/2x3 +1/3x4 +1/4x5 +1/5x6
1\2x3+1\3x4+1\4x5+1\5x6
1/2x3 + 1/3x4 + 1/4x5...+ 1/9x10
1/ 2x3+ 1/ 3x4+ 1/ 4x5.....+ 1/ 9x10 =
giúp mình giải câu này với!!
A = 1 /2x3 + 1/3x4 + 1/4x5 + 1/5x6 + 1/7x8 + 1/8x9
☹ 1/ 2x3 + 1/ 3x4 + 1/ 4x5 + 1/ 5x6 ☹ giúp mk
Tính nhanh :
A = 1/1x2 + 1/2x3 + 1/3x4 + 1/4x5 + ........1/98x99 + 1/99x100 .