a) \(2,8\times19,35-2,8\times19,35\)

\(=2,8\times\left(19,35-19,35\right)\)

\(=2,8\times0\)

\(=0\)

b) \(56,08\times93,23-56,08\times83,23\)

\(=56,08\times\left(93,23-83,23\right)\)

\(=56,08\times10\)

\(=560,8\)

c) \(1,3856\times194-1,3856\times94\)

\(=1,3856\times\left(194-94\right)\)

\(=1,3856\times100\)

\(=138,56\)

d) \(28,524\times3,8+28,524\times6,2\)

\(=28,524\times\left(6,2+3,8\right)\)

\(=28,524\times10\)

\(=285,24\)

c) \(101\times0,128-0,128\)

\(=0,128\times\left(101-1\right)\)

\(=0,128\times100\)

\(=12,8\)

a: =2.8*(19,35-19,35)=0

b: =56,08(93,23-83,23)

=10*56,08=560,8

c: =1,3856(194-94)

=1,3856*100

=138,56

d: =28,524*(3,8+6,2)

=28,524*10

=285,24

e: =0,128*100

=12,8

a, 2,8 x 19,35 - 2,8 x 19,35

=2,8 x (19,35 - 19,35) 

= 2,8 x 0 = 0                            

b, 56,08 x 93,23 - 56,08 x 83,23

= 56,08 x  (93,23 - 83,23)

= 56,08 x 10

= 560,8

c, 1,3856 x 194 - 1,3856 x 94

= 1,3856 x (194 - 94)

= 1,3856 x 100

= 138,56                       

d, (28,524 x 3,8 + 28,524 x 6,2)

= 28,524  x (3,8 + 6,2)

= 28,524 x 10

= 285,24

e,101 x 0,128 - 0,128

= (101 - 1) x 0,128

= 100 x 0,128

=12,8

431/225

9/5 x 5/7=63/25

63/25 x 7/9=431/225

chúc học tốt

d) \(202\times19-9\times202=202\times\left(19-9\right)=202\times10=2020\)

    \(202\times19-9\times202=3838-1818=2020\)

202 x 19 - 9 x 202

= 3838 - 1818

= 2020

202 x ( 19-9)

= 202 x 10

= 2020

c1 202 *( 19-9) 

= 202*10= 2020

Cách 2 bạn tính bth thui nhân chia trước cộng trừ sau 

1.

a) \(x^3-\frac{1}{2}=\left(-\frac{3}{8}\right)\)

\(\Rightarrow x^3=\left(-\frac{3}{8}\right)+\frac{1}{2}\)

\(\Rightarrow x^3=\frac{1}{8}\)

\(\Rightarrow x^3=\left(\frac{1}{2}\right)^3\)

\(\Rightarrow x=\frac{1}{2}\)

Vậy \(x=\frac{1}{2}.\)

b) \(\left(2x-1\right)^3=-8\)

\(\Rightarrow\left(2x-1\right)^3=\left(-2\right)^3\)

\(\Rightarrow2x-1=-2\)

\(\Rightarrow2x=\left(-2\right)+1\)

\(\Rightarrow2x=-1\)

\(\Rightarrow x=\left(-1\right):2\)

\(\Rightarrow x=-\frac{1}{2}\)

Vậy \(x=-\frac{1}{2}.\)

c) \(17+3^x=98\)

\(\Rightarrow3^x=98-17\)

\(\Rightarrow3^x=81\)

\(\Rightarrow3^x=3^4\)

\(\Rightarrow x=4\)

Vậy \(x=4.\)

Chúc bạn học tốt!

Chó

=(84,35- 19,35) + (32,18 - 27,18)

=65+5

=70

Gọi công thức cần tìm là: \(Na_xS_yO_z\left(H_2O\right)_t\) theo đề bài ta có:

\(\dfrac{23x}{0,1854}=\dfrac{32y}{0,2582}=\dfrac{16z}{0,1935}=\dfrac{18t}{0,3629}\)

\(\Leftrightarrow x=y=\dfrac{2z}{3}=\dfrac{2t}{5}\)

Chọn \(\left\{{}\begin{matrix}x=y=2\\z=3\\t=5\end{matrix}\right.\)

Vậy công thức cần tìm là: \(Na_2S_2O_3.5H_2O\)

Sr mình làm sai mất !