1) 43 . 78 - 43 . 48 + 30 . 80 - 30 . 23

= 43.(78 - 48) + 30.(80 - 23)

= 43.30 + 30.57

= 30.(43 + 57)

= 30.100

= 3000

2) 31.175 - 31.50 + 69.125

= 31.(175 - 50) + 69.125

= 31.125 + 69.125

= 125.(31 + 69)

= 125.100

= 12500

3) 2.[(7 - 3¹³ : 3¹²) : 2² + 99] - 10²

= 2.[(7 - 3) : 4 + 99] - 100

= 2.(4 : 4 + 99) - 100

= 2.(1 + 99) - 100

= 2.100 - 100

= 200 - 100

= 100

4) 2²⁰¹⁹.2² : 2²⁰¹⁶ - 125 : 5² + 2019⁰

= 2²⁰²¹ : 2²⁰¹⁶ - 125 : 25 + 1

= 2⁵ - 5 + 1

= 32 - 4

= 28

a,\(\dfrac{2}{3}\)-\(\dfrac{5}{7}\).\(\dfrac{14}{25}\)

=\(\dfrac{2}{3}\)-\(\dfrac{2}{5}\)

=\(\dfrac{4}{15}\)

b,\(\dfrac{-2}{5}\).\(\dfrac{5}{8}\)+\(\dfrac{5}{8}\).\(\dfrac{3}{5}\)

=\(\dfrac{5}{8}\).(\(\dfrac{-2}{5}\)+\(\dfrac{3}{5}\))

=\(\dfrac{5}{8}\).\(\dfrac{1}{5}\)

=\(\dfrac{1}{8}\)

Giải:

a) \(\dfrac{2}{3}-\dfrac{5}{7}.\dfrac{14}{25}=\dfrac{2}{3}-\dfrac{2}{5}=\dfrac{4}{15}\) 

b) \(\dfrac{-2}{5}.\dfrac{5}{8}+\dfrac{5}{8}.\dfrac{3}{5}\) 

\(=\dfrac{5}{8}.\left(\dfrac{-2}{5}+\dfrac{3}{5}\right)\) 

\(=\dfrac{5}{8}.\dfrac{1}{5}\) 

\(=\dfrac{1}{8}\) 

c) \(\left(\dfrac{1}{2}\right)^2-1\dfrac{1}{2}+0,5.\dfrac{12}{5}+5\%\) 

\(=\dfrac{1}{4}-\dfrac{3}{2}+\dfrac{1}{2}.\dfrac{12}{5}+\dfrac{1}{20}\) 

\(=\dfrac{-5}{4}+\dfrac{6}{5}+\dfrac{1}{20}\) 

\(=0\) 

Chúc bạn học tốt!

c,\(\left(\dfrac{1}{2}\right)^2\)-1\(\dfrac{1}{2}\)+0,5.\(\dfrac{12}{5}\)+5%

=\(\dfrac{1}{4}\)-\(\dfrac{3}{2}\)+\(\dfrac{1}{2}\).\(\dfrac{12}{5}\)+\(\dfrac{1}{20}\)

=\(\dfrac{1}{4}\)-\(\dfrac{3}{2}\)+\(\dfrac{6}{5}\)+\(\dfrac{1}{20}\)

=\(\dfrac{-5}{4}\)+\(\dfrac{6}{5}\)+\(\dfrac{1}{20}\)

=\(\dfrac{-1}{20}\)+\(\dfrac{1}{20}\)

=0

=

22/ \(\omega A=8\pi\)

\(A^2=x^2+\dfrac{v^2}{\omega^2}\Leftrightarrow A^2=3,2^2+\dfrac{\left(4,8\pi\right)^2}{\omega^2}\)

\(\Leftrightarrow\omega^2A^2=3,2^2\omega^2+23,04\pi^2\Leftrightarrow64\pi^2=3,2^2.\omega^2+23,04\pi^2\Leftrightarrow\omega=2\pi\left(rad/s\right)\)

\(\Rightarrow f=\dfrac{\omega}{2\pi}=\dfrac{2\pi}{2\pi}=1\left(Hz\right)\Rightarrow D.1Hz\)

23/ \(\omega A=20;\omega^2A=80\Rightarrow\left\{{}\begin{matrix}\omega=4\left(rad/s\right)\\A=5cm\end{matrix}\right.\)

\(\Rightarrow v=\omega\sqrt{A^2-x^2}=4.\sqrt{5^2-4^2}=12\left(cm/s\right)\Rightarrow A.12cm/s\)

1 Ann is very upset because the local authorities have turned down her proposals to install solar panels to supply electricity for traffic lights

2 A committe has been set up to examine the question

3 Our class football team lost the match, so we tried to cheer them up

4 "Can I wear jeans at wedding party?" - "Of course not. You'll have to cover up smart clothes"

Ann is very upset because the local authorities have turned down her proposals to install solar panels to supply electricity for traffic lights

A committe has been set up to examine the question

Our class football team lost the match, so we tried to spirit them up /cheer them up

"Can I wear jeans at wedding party?" - "Of course not. You'll have to cover up smart clothes"

Before I come to a decision, I'll have to think over their offer very carefully

1.Ann is very upset because the local authorities have turned down her proposals to install solar panels to supply electricity for traffic lights.

2.A committe has been set up to examine the question.

3.Our class football team lost the match, so we tried to cheer them up,

4.''Can I wear jeans at wedding party?'' - ''Of course not.You'll have to cover up smart clthes''

5.Before I come to a decision, I'll have to think over their offer very carefully.