`( 5/6 -1/2 ) : 2/3`
`= ( 5/6 - 3/6) xx 3/2`
`= 1/3 xx 3/2`
`= 3/6`
`=1/2`
`@ `
`(5/6-1/2) : 2/3`
`= 5/6 : 2/3 - 1/2 : 2/3`
`= 5/6 xx 3/2 - 1/2 xx 3/2`
`= 15/12 - 3/4`
`= 5/4 -3/4`
`= 2/4`
`=1/2`
`------`
`(3/4 +1/2) : 3/5`
`= ( 3/4 + 2/4) xx 5/3`
`= 5/4 xx 5/3`
`= 25/12`
`@ `
`(3/4 + 1/2) : 3/5`
`= 3/4 : 3/5 + 1/2 : 3/5`
`= 3/4 xx 5/3 + 1/2 xx 5/3`
`= 5/4 + 5/6`
`=25/12`
giai ho bai giai bang hai cach: (3/4+1/2):3/4
1+2+3+4++5+6+7+8+9+10+11+12+13+14++15+16+17+18+19+20
Hoi tong tren bang bao nhieu (tinh nhanh va giai thich cach lam)
bai 1 : tinh bang hai cach
a) 3/22 x3/11 x22 =??
b)( 1/2 + 1/3 ) x2/5 =???
c)
3/5 x 17/21 + 17/21 x 2/5 =???
giai bai toan sau:Co 38 chiec but gom hai loai :mau xanh va mau do.Biey rang 2/3 so but xanh bang 3/5 so but do.Tim so but moi loai?
giai chi tiet bai toan.
1+2-3+4-5+6-7+8-9+10...19+20 tinh nhanh bang bao nhieu giai thich cach lam
giai bang hai cach
( 1/3 + 1/5 ) x 1/2
tinh bang cach thuan tien nhat a.3/5+4/7+2/5+1/7+2/7 b.1/3+1/6+4/3+2/6+2/3
tinh bang hai cach a)3/4 x 1/2 x 2
cach 1 : .....................................................
cach 2 : .....................................................
b) (3/4 + 1/2) x 5?7
cach 1 : .................................................................
cach 2 : .................................................................
bai 4: tinh bang cach thuan tien nhat: a, 5/9*5/2+4/9*5/2 , b, 12*3/4-3/4*12/7 lam kieu gi
giup minh voi
