A=1/3+1/2+1/6+1/12+1/20+......+1/110+1/132+2/3
Tính nhanh
1/2+1/6+1/12+1/20+...+1/90+1/110+1/132
1/2+1/6+1/12+1/20+...+1/90+1/110+1/132
mk giải như thề này đ ko ạ
Bài 3 : Tính nhanh :
a ) A = 2 + 4 + 6 + 8 + ....+ 1000
b ) 1/ 20 + 1/30 + 1/42 + 1/50 + 1/72 + 1/90 + 1/110 + 1/132
c ) 2 / 1x3 + 2 / 3x5 + 2/5 x 7 + .....+ 2 / 97 x 99 + 2/99 x 101
1/2 cộng 1/6 cộng 1/12 cộng .... cộng 1/132
1/90 cộng 1/110 cộng 1/132 cộng ..... cộng 1/10100
a) (y+1/3)+(y+2/9)+(y+1/27)+(1/81)=56/81
b) (1/2+1/4+1/8+1/16):y=1/2+1/6+1/12+1/20+...+1/132
1/12 + 1/20 + 1/42 + 1/56 + 1/72+ 1/90 + 1/110 + 1/132
a} 3/20+3/30 + 3/42 + ....3/110+3/132
b} 17/36 . 13/15+ 12/15 - 17/36 - 1/36
\(\frac{1}{2}\)+\(\frac{1}{6}\)+\(\frac{1}{12}\)+\(\frac{1}{20}\)+......+\(\frac{1}{110}\)+\(\frac{1}{132}\)