3+2+2+2x8-1+4x1
(1/1x1/2) + (1/2x1/3) + (1/3x1/4) + (1/4x1/5) +....+ (1/72x1/73) =
`@Fù`
`=1/(1×2)+1/(2×3)+1/(3×4)+...+1/(72×73)`
`=1/1-1/2+1/2-1/3+...+1/72-1/73`
`=1-1/73`
`=72/73`
1/1x1/2+1/2x1/3+1/3x1/4+1/4x1/5+1/5x1/6
= 1/1x2 + 1/2x3 + 1/3x4 + 1/4x5 + 1/5 x 6
= (1 - 1/2) + (1/2 - 1/3) + (1/3 - 1/4) + (1/4 - 1/5) + (1/5 - 1/6)
= 1 - 1/6
= 5/6
nha,mơn nhìu
\(\frac{1}{1}x\frac{1}{2}+\frac{1}{2}x\frac{1}{3}+\frac{1}{3}x\frac{1}{4}+\frac{1}{4}x\frac{1}{5}+\frac{1}{5}x\frac{1}{6}\)
\(=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}\)
\(=1-\frac{1}{6}=\frac{5}{6}\)
Tính:(1-1/2x1/2)x(1-1/3x1/3)x(1-1/4x1/4)x…x(1-1/2007x1/2007)
(1-1/2x1/2)x(1-1/3x1/3)x(1-1/4x1/4)x…x(1-1/2007x1/2007) = ( 1 - 1/4 ) x ( 1 - 1/9 ) x ( 1- 1/16) x .....x ( 1 - 1/4028049) = 3/4 x 8/9 x 15/16 x .....x 4028048 / 4028049 = 3 x 8 x 15 x .....x 4028048 / 4 x 9 x 16 x ......x 4028049 = 1 x 3 x 2 x 4 x 3 x 5 x .....x 2006 x 2008 / 2x2 x 3 x3 x 4 x 4 x .....x 2007 x 2007 = ( 1 x 2 x 3 x .....x 2006) x ( 3 x 4 x 5 x .....x 2008) / ( 2 x 3 x 4 x ....x 2007) x ( 2 x 3 x 4 x ....x 2007) = 2008 / 2007 x 2 = 1004 / 2007
Tính:
(1-1/2x1/2)x(1-1/3x1/3)x(1-1/4x1/4)x…x(1-1/2007x1/2007)
(1-1/2x1/2)x(1-1/3x1/3)x(1-1/4x1/4)x…x(1-1/2007x1/2007)
= ( 1 - 1/4 ) x ( 1 - 1/9 ) x ( 1- 1/16) x .....x ( 1 - 1/4028049)
= 3/4 x 8/9 x 15/16 x .....x 4028048 / 4028049
= 3 x 8 x 15 x .....x 4028048 / 4 x 9 x 16 x ......x 4028049
= 1 x 3 x 2 x 4 x 3 x 5 x .....x 2006 x 2008 / 2x2 x 3 x3 x 4 x 4 x .....x 2007 x 2007
= ( 1 x 2 x 3 x .....x 2006) x ( 3 x 4 x 5 x .....x 2008) / ( 2 x 3 x 4 x ....x 2007) x ( 2 x 3 x 4 x ....x 2007)
= 2008 / 2007 x 2
= 1004 / 2007
A=3/2^2x8/3^2x15/4^2....899/30^2
tính tích A
a 3/4x2/9+1/3 b 5/4:2.9+1/2 c 7/2-1/4x1/5 d 5/4+1/5:2/3
giúp mik nha mình sắp phải nộp rồi
Câu hỏi
a)3/4 x 2/9 + 1/3
=1/6 + 1/3
=1/6 + 2/6
=1/2
b)5/4:2.9+1/2
=1.25 : 2.9 + 1/2
=25/58 + 1/2 =27/29
c)7/2 - 1/4 x 1/5
=7/2 - 1/20
=69/20
d)5/4+1/5:2/3
=5/4 + 3/10
=31/20
Học tốt!
câu hỏi là tính
7/2x3/4+17/8x2/3+3/4x1/2+7/8x3/3
\(\dfrac{7}{2}\times\dfrac{3}{4}+\dfrac{17}{8}\times\dfrac{2}{3}+\dfrac{3}{4}\times\dfrac{1}{2}+\dfrac{7}{8}\times\dfrac{3}{3}\)
\(=\dfrac{7\times3}{2\times4}+\dfrac{17\times2}{8\times3}+\dfrac{3\times1}{4\times2}+\dfrac{7}{8}\times1\)
\(=\dfrac{21}{8}+\dfrac{17}{12}+\dfrac{3}{8}+\dfrac{7}{8}\)
\(=\left(\dfrac{21}{8}+\dfrac{3}{8}+\dfrac{7}{8}\right)+\dfrac{17}{12}\)
\(=\dfrac{31}{8}+\dfrac{17}{12}\)
\(=\dfrac{31\times3}{8\times3}+\dfrac{17\times2}{12\times2}\)
\(=\dfrac{93}{24}+\dfrac{34}{24}\)
\(=\dfrac{127}{24}\)
So sánh 2 phép tính sau:
a)2x4 và 2x8;
b)2x9 và 2x2;
c)2+2x2 và 2x8+9.
a) 2 x 4 và 2 x 8
2 x 4 = 8
2 x 8 = 16
=> 2 x 4 < 2 x 8
Dễ ẹc:
a) 2 x 4 = 8
2 x 8 = 16
Mà 8 < 16
=> 2 x 4 < 2 x 8
b) 2 x 9 = 18
2 x 2 = 4
Mà 18 > 4
=> 2 x 9 > 2 x 2
c) 2 + 2 x 2 = 2 + 4 = 6
2 x 8 + 9 = 16 + 9 = 25
Mà 6 < 25
=> 2 + 2 x 2 < 2 x 8 + 9
a) Ta có : 2 x 4 = 8
2 x 8 = 16
Vì 8 < 16 \(\Rightarrow\)2 x 4 < 2 x 8
b) Ta có : 2 x 9 = 18
2 x 2 = 4
Vì 18 > 4 \(\Rightarrow\)2 x 9 > 2 x 2
c) Ta có : 2 + 2 x 2 = 2 + 4 = 6
2 x 8 + 9 = 16 + 9 = 25
Vì 6 < 25 \(\Rightarrow\)2 + 2 x 2 < 2 x 8 + 9
tính:
a).1/2x1/4x1/6
b).1/2x1/4:1/6
c).1/2:1/4x1/6
ai làm đầy đủ phép tính đáp án mik tick 2!!!nói luôn ra đáp án mik ko tick
Tính
a ) 1/2 x 1/4 x 1/6
= 1/8 x 1/6
= 1/48
b ) 1/2 x 1/4 : 1/6
= 1/8:1/6
3/4
c ) 1/2 : 1/4 x 1/6
= 2 x 1/6
= 1/3
tk mk nha ( nếu đúng )
hihi mơn nha !!!!!!!!!
a, : 1/2 x 1/4 x 1/6 = 1/8 x 1/6 = 1/48
b, ; 1/2 x 1/4 : 1/6 = 1/8 : 1/6 = 6/8 = 3/4
c, 1/2 : 1/4 x 1/6 = 4/2 x 1/6 = 4/12 = 1/3