\(\frac{4}{6}\cdot10+\frac{6}{10}\cdot16+\frac{1}{16}\cdot3+\frac{1}{24}\cdot7+\frac{1}{28}\cdot5\)

đề bài như này hả

\(\dfrac{6}{3\cdot5}+\dfrac{6}{5\cdot7}+\dfrac{6}{7\cdot9}+.....+\dfrac{6}{33\cdot35}\)

\(=\left(\dfrac{2}{3\cdot5}+\dfrac{2}{5\cdot7}+\dfrac{2}{7\cdot9}+...+\dfrac{2}{33\cdot35}\right)\cdot3\)

\(=\left(\dfrac{1}{3}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{7}+.....+\dfrac{1}{33}-\dfrac{1}{35}\right)\cdot3\)

\(=\left(\dfrac{1}{3}-\dfrac{1}{35}\right)\cdot3\)

\(=\dfrac{32}{3\cdot35}\cdot3\)

\(=\dfrac{32}{35}\)

\(\dfrac{8\times3\times4}{16\times3}=\dfrac{8\times3\times4}{4\times4\times3}=\dfrac{8}{4}=\dfrac{2\times2\times2}{2\times2}=2\)

\(\)

\(\dfrac{6}{5.7}+\dfrac{6}{7.9}+...+\dfrac{6}{59.61}\)

\(=3\left(\dfrac{2}{5.7}+\dfrac{2}{7.9}+...+\dfrac{2}{59.61}\right)\)

\(=3\left(\dfrac{1}{5}-\dfrac{1}{7}+\dfrac{1}{7}-\dfrac{1}{9}+...+\dfrac{1}{59}-\dfrac{1}{61}\right)\)

\(=3\left(\dfrac{1}{5}-\dfrac{1}{61}\right)\)

\(=\dfrac{3.56}{305}\\ =\dfrac{168}{305}\)

\(=3\left(\dfrac{1}{5}-\dfrac{1}{7}+\dfrac{1}{7}-\dfrac{1}{9}+...+\dfrac{1}{59}-\dfrac{1}{61}\right)=3\cdot\left(\dfrac{1}{5}-\dfrac{1}{61}\right)=3\cdot\dfrac{56}{305}=\dfrac{168}{305}\)

\(\dfrac{8.3.4}{8.2.3}=\dfrac{4}{2}=2\)

b. \(\dfrac{5.6.5.5.7.8}{5.5.3.8.4.3.4.7}=\dfrac{5}{12}\)

Gọi 2 số cần tìm là a và b ( a< b ) 

Thay  1/2 ×a = 1/4×b  

<=>   a = (1/4×b )/(1/2)

Vào a + b = 2022 

Ta được : (1/4 × b ) / ( 1/2) + b =  2022 ( bấm máy tính ra b hay dạng bài tìm x , tìm được b )

Rồi lấy 2022 - b = a 

( tìm được a )

chụi

( 16 x 6 + 16 x 3 + 16 ) - ( 12 x 65 + 12 x 3 + 2 x 12 )

= 16 x 10 - ( 780 + 12 x 5 )

= 160 - ( 780 + 60 )

= 160 - 840

= - 680

Kết          quả         là 

          -680

     Đáp          số........

( 16 x 6 + 16 x 3 + 16 ) - ( 12 x 65 + 12 x 3 + 2 x 12 )

= [ 16 x ( 6 + 3 + 1 )] - [ 12 x ( 65 + 3 + 2 )]

= [ 16 x 10 ] - [ 12 x 70 ]

= 160 - 840

= -680

43/30

14/15

35/24

42/5

43/30

14/15

35//24

42/5

43/30

14/15

35/24

42/5

B=x⁵-15x⁴+16x³-29x²+13x

B= 14⁵-15.14⁴+16.14³-29.14²+13.14

B=14.14⁴-15.14⁴+16.14³-29.14²+13.14

B=(14-15).14⁴+16.14³-29.14²+13.14

B= (-1).14⁴+16.14³-29.14²+13.14

B= (-1).14⁴+16.14².14-29.14²+13.14

B=(-1).14⁴+224.14²-29.14²+13.14

B= (-1).14⁴+(224-29).14²+13.14

B=(-1).14⁴+195.14²+13.14

B=[(-1).14³].14+195.14.14+13.14

B= (-2744).14+2730.14+13.14

B= 14.[(-2744)+2730+13]

B= 14.(-1)

B= -14