\(\dfrac{5}{8}\) x 4 + \(\dfrac{5}{8}\) x \(\dfrac{4}{5}\)

= \(\dfrac{5}{8}\) x (\(4\) + \(\dfrac{4}{5}\) )

= \(\dfrac{5}{8}\) x \(\dfrac{24}{5}\) = 3

\(\dfrac{5}{8}\times4+\dfrac{5}{8}\times\dfrac{4}{5}\)
\(=\dfrac{5}{8}\times\left(4+\dfrac{4}{5}\right)\)
\(=\dfrac{5}{8}\times\dfrac{24}{5}\)
\(=\dfrac{24}{8}\)
\(=3\)

5/8 * 4 + 5/8 * 4/5 

= 5/8 * (4+4/5)

= 5/8 * 24/5

= 3

\(\frac{1}{8}.\frac{4}{5}-1=\frac{1}{10}-1=\frac{-9}{10}\)

Dễ :v

1/8x4/5-1= -9/10

B . 8 x 4 = 32

Bn phải lấy số con gà mỗi chuồng nhân với số chuồng thì mới đúng

8x4 =32

A, 4*8=32

A = 1/3×5 + 1/5×7 + 1/7×9 + 1/9×11 + ... + 1/29×31

2A = 2/3×5 + 2/5×7 + 2/7×9 + 2/9×11 + ... + 2/29×31

2A = 1/3 - 1/5 + 1/5 - 1/7 + 1/7 - 1/9 + 1/9 - 1/11 + .... + 1/29 - 1/31

2A = 1/3 - 1/31

2A = 31/93 - 3/93 = 28/93

A = 28/93 : 2

A = 28/93 × 1/2 = 14/93

B = 2/1×4 + 2/4×7 + 2/7×10 + ... + 2/31×34

3/2B = 3/1×4 + 3/4×7 + 3/7×10 + ... + 3/31×34

3/2B = 1 - 1/4 + 1/4 - 1/7 + 1/7 - 1/10 + ... + 1/31 - 1/34

3/2B = 1 -1/34 = 33/34

B = 33/34 : 3/2

B = 33/34 × 2/3 = 11/17

\(A=\frac{1}{3\times5}+\frac{1}{5\times7}+\frac{1}{7\times9}+...+\frac{1}{29\times31}\)

   \(=\frac{1}{2}\times\left(\frac{1}{3}-\frac{1}{5}\right)+\frac{1}{2}\times\left(\frac{1}{5}-\frac{1}{7}\right)+...+\frac{1}{2}\times\left(\frac{1}{29}-\frac{1}{31}\right)\)

   \(=\frac{1}{2}\times\left(\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+...+\frac{1}{29}-\frac{1}{31}\right)\)

   \(=\frac{1}{2}\times\left(\frac{1}{3}-\frac{1}{31}\right)\)

   \(=\frac{1}{2}\times\frac{28}{93}\)

   \(=\frac{14}{93}\)

\(B=\frac{2}{1\times4}+\frac{2}{4\times7}+...+\frac{2}{31\times34}\)

   \(=\frac{1}{3}\times\left(\frac{2}{1}-\frac{2}{4}\right)+\frac{1}{3}\times\left(\frac{2}{4}-\frac{2}{7}\right)+...+\frac{1}{3}\times\left(\frac{2}{31}-\frac{2}{34}\right)\)

   \(=\frac{1}{3}\times\left(2-\frac{2}{4}+\frac{2}{4}-\frac{2}{7}+...+\frac{2}{31}-\frac{2}{34}\right)\)

   \(=\frac{1}{3}\times\left(2-\frac{2}{34}\right)\)

   \(=\frac{1}{3}\times\frac{33}{17}\)

   \(=\frac{11}{17}\)

2 phép hay 1 phép zậy bn

2 nha

8x⁴ + x = 0

<=> x( 8x³ + 1 ) = 0

<=> x ( 2x + 1 ) ( 4x² - 2x + 1 ) = 0 

<=> x = 0 hoặc 2x + 1 = 0 hoặc 4x² - 2x + 1 = 0 ( mà 4x² - 2x + 1 luôn khác 0 )

= > x = 0 hoặc x = -1/2 

Vậy S = { -1/2;0}

a)=1x2x3x4x5/2x3x4x5x6 =1/6

b)=1x2x3x4x5x6x7x8x9/10x9x8x7x6x5x4x3 x2=1/10

\(\left(2x+1\right)^2+\left|y-1,2\right|=0\)(1)

Ta thấy:\(\hept{\begin{cases}\left(2x+1\right)^2\ge0\\\left|y-1,2\right|\ge0\end{cases}}\)

\(\left(2x+1\right)^2+\left|y-1,2\right|\ge0\)(2)

Từ (1) và (2) suy ra \(\hept{\begin{cases}\left(2x+1\right)^2=0\\\left|y-1,2\right|=0\end{cases}}\)\(\Rightarrow\hept{\begin{cases}2x+1=0\\y-1,2=0\end{cases}}\)\(\Rightarrow\hept{\begin{cases}x=-\frac{1}{2}\\y=1,2\end{cases}}\)

\(\Rightarrow x+y=-\frac{1}{2}+1,2=-0,5+1,2=0,7\)

ai giúp mik với ak mik cần gấp

\(\dfrac{1}{1.4}+\dfrac{1}{4.2}+\dfrac{1}{2.8}+\dfrac{1}{8.4}+\dfrac{1}{4.16}+\dfrac{1}{16.8}\)

= \(\dfrac{1}{4}.\left(1+\dfrac{1}{2}+\dfrac{1}{4}+\dfrac{1}{8}+\dfrac{1}{16}+\dfrac{1}{32}\right)\)

= \(\dfrac{1}{4}.\left(\dfrac{3}{2}+\dfrac{3}{8}+\dfrac{3}{32}\right)\)

= \(\dfrac{1}{4}.\dfrac{3}{2}\left(1+\dfrac{1}{4}+\dfrac{1}{16}\right)\)

= \(\dfrac{1}{4}.\dfrac{3}{2}\left(\dfrac{16}{16}+\dfrac{4}{16}+\dfrac{1}{16}\right)\)

= \(\dfrac{3}{8}.\dfrac{21}{16}\)

= \(\dfrac{63}{128}\)