tinh nhanh va thuan tien:
(1-1/2):(1-1/3):(1-1/4):(1-1/5):(1-1/6)
4+9+8+6+2+1+3+7=
tinh nhanh va thuan tien
ai nhanh va day du nhat thi minh tk cho
4+9+8+6+2+1+3+7 = (4+6) + ( 9+1) + ( 8+2 ) + (7+3)
= 10 + 10 + 10 +10
= 40
4 + 9 + 8 + 6 + 2 + 1 + 3 + 7 = ( 4 + 6 ) + ( 9 + 1 ) + ( 8 + 2 ) + ( 3 + 7 )
= 10 + 10 + 10 + 10
= 10 x 4
= 40
= (4+6) +(9+1)+(8+2)+(3+7)
=10+10+10+10
=10x4
=40
k nhé
Tinh bang cach thuan tien nhat :
a) 1/3 + 1/4 + 2/3 + 3/4
b) 1/2 + 1/3 - 1/5 + 1/6
a)1 /3 +1/4+2/3+3/4=\(\frac{1}{3}\)+\(\frac{2}{3}\)+\(\frac{1}{4}\)+\(\frac{3}{4}\)=1+1=2
b)1/2 +/3 -/5 +1/6=4/5
a,1/3+1/4+2/3+3/4
=(1/3+2/3)+(1/4+3/4)
= 1 + 1
= 2
nha, còn phàn b mình chưa biết
a)\(\frac{1}{3}\)+\(\frac{1}{4}\)+\(\frac{2}{3}\)+\(\frac{3}{4}\)
=(\(\frac{1}{3}\)+\(\frac{2}{3}\))+(\(\frac{1}{4}\)+\(\frac{3}{4}\))
=1+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
BAI 1 : TINH NHANH BANG CACH THUAN TIEN NHAT :
A} 13/4 + 7/12 + 3/4 + 17/12
B} 1 VA 2/3 + 4 VA 4/7 + 5 VA 1/3 + 6 VA 3/7
C} 3/4 * 7/9 = 3/4 * 2/9
D} 3/4 * 4/5 * 5/6
BAI 3 : TINH
A} 3/4 CUA 16 KG .....
B} 7/12 CUA 840 M .....
C} 13/15 CUA 135 M3 .....
D} 6/7 CUA 280 L......
Tinh bang cach thuan tien nhat:
a) 1/3 + 1/4 + 2/3 + 3/4
b) 1/2 + 1/3 - 1/5 + 1/6
c) 2/3 x 4/5 + 1/3 x 4/5
d) 2/3 x 4/5 - 1/3 x 4/5
a)1/3+1/4+2/3+3/4
=(1/3+2/3)+(1/4+3/4)
=1+1
=2.
b)1/2+1/3-1/5+1/6
=(1/2+1/3+1/6)-1/5
=1-1/5
=4/5
c)2/3x4/5+1/3x4/5
=4/5x(2/3+1/3)
=4/5x1
=4/5
d)2/3x4/5-1/3x4/5
=4/5x(2/3-1/3)
=4/5x1/3
=4/15
Tinh bang cach thuan tien nhat
1/2+2+1/2×4+1/2×4
3/9+4/3+1/3×5
0.6+0.9+0.3×5
1+2+3+4+5+6+7+8+9
tinh bang cach thuan tien nhat
1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9
= (1 + 9) + (2 + 8) + (3 + 7) + (4 + 6) +5
= 10 + 10 + 10 +10 + 5
= 10 x 4 + 5
= 40 + 5
= 45
1+2+3+4+5+6+7+8+9
=[1+9]+[2+8]+[3+7]+[4+6]+5
=10+10+10+10+5
=40+5
=45
Tinh gia tri bieu thuc : 170 + 9 + 6/100 + 3/10 ; tinh bang cach thuan tien : 1/2 : 0.5 - 1/4 : 0.25 + 1/8 : 0.125 - 1/10 : 0.1
tinh bang cach thuan tien nhat
1/2+1/6+1/12+1/20
1/2+1/6+1/12+1/20+..........+1/9900
1/2+1/3+1/4+1/8+1/16
1/2+1/3+1/4+1/8+1/16+........+1/512
\(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}\)
\(=\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}\)
\(=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+\frac{1}{5}\)
\(=1-\frac{1}{5}\)
\(=\frac{4}{5}\)
\(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+...+\frac{1}{9900}\)
\(=\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+...+\frac{1}{98.99}+\frac{1}{99.100}\)
\(=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+....+\frac{1}{98}-\frac{1}{99}+\frac{1}{99}-\frac{1}{100}+\frac{1}{100}\)
\(=1-\frac{1}{100}\)
\(=\frac{99}{100}\)