tinh nhanh :1/1*2+1/2*3+1/3*4+1/4*5+1/5*6
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
1.tinh nhanh
a=1/2+1/6+1/12+1/20+1/30+1/42
2.tim x
a)7/4-x nhân 4/3=5/19
b)(x+3/4) nhân 5/7=10/9
c)x nhân 1/2 +3/2 nhân x=4/5
toán nâng cao lớp 4
a) Tinh gia tri bieu thuc:
3/5 : 4/5 + 1/2 x 2/3
b) Tim x:
5/4 nhan x = 3/8 + 1/4
3 Tinh
6/5-1/5 cong 1/4
1/2-1/4 cong 2/3
3/5 cong 4/9 -1/3
Bai 1 : tinh
a . 6/7 + 5/8 : b. 3/5 - 3/8 ; c. 1/4 + 5/6 ; d. 4/9 - 1/6
Bai 2 : tinh
a. 3 + 2/5 ; b. 4 - 5/7 ;
c. 1 - [2/5 + 1/3] .
tinh nhanh phan so
1/2*3+1/3*4+1/4*5+1/5*6+1/6*7+1/7*8
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 : .................................................................
Tinh băng cach thuan tiện nhất
1/2 x 1/3 + 1/3x1/4 + 1/4 x 1/5 + 1/5 x1/6