Thuc hien phep tinh bang cach tinh nhanh :
a) 4/9 + 3/2 + 6/36.
b) 2/7 x 5/17 + 12/7 x 15/17.
c) 2,34 + 5,18 + 7,66.
d) 7/11 : 3/4 + 7/11 : 1/4.
GIUP MINH MINH DANG CAN GAP.
a[11+13+15+17+19]-/10+12+14+16+18]
b /9+7+5+3+1]-/8+6+4+2]
1+[2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17]*0,000001
1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19+20=?
tính thuận tiện
a ( 145 * 99 - 145 ) - ( 143 * 101 - 143 )
b ( 500 * 9 - 250 * 18 ) * ( 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 +9 )
c ( 11 + 12 + 13 + 14 + 15 + 16 + 17 + 18 + 19 ) * ( 6 * 8 - 48)
1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19=?
5/6 + 7/8
2+2/3
7/9 - 1/7
1-1/11
2 x 17/81
9/11 : 5/6
3:12/25
mong mn trả lời giúp ạ
a/2-3+5-7+9-11+13-15+17
b/1/1×2+1/2×3+1/3×4+1/4×5+1/5×6+1/6×7+1/7+8+1/8×9
1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10
2 + 4 + 6 + 8 + 10 + 12 + 14 + 16 + 18 + 20
1 + 3 + 5 + 7 + 9 + 11 + 13 + 15 + 17 + 19