1+5+7+48+5+2+5+5+566+54+4+4+54+54=814

a) 3⁴ . 54-3⁴ . 54⁰

^{=3^4.(54-54^0)}

^{=3^4.(54.1)}

^=81.54=4374

30.54.30.1

=30.(54.1)

=54.30

=1620

3. 31-[26-(2017+35)]

=31-26-2017+35

=(31-26+35)-2017

=40-2017

=-1977

4. 54+(-37+10-54+67)

=54-37+10-54+67

=(54-54)-(37-67)+10

=0+30+10

=40

a) \(\dfrac{2}{5}=\dfrac{2\times3}{5\times3}=\dfrac{6}{15}=\dfrac{2}{5}\)

\(\dfrac{4}{7}=\dfrac{4\times2}{7\times2}=\dfrac{8}{14}=\dfrac{4}{7}\)

\(\dfrac{13}{54}=\dfrac{13\times3}{54\times3}=\dfrac{39}{162}=\dfrac{13}{54}\) 

b) \(\dfrac{8}{20}=\dfrac{8:4}{20:4}=\dfrac{2}{5}\)

\(\dfrac{10}{16}=\dfrac{10:2}{16:2}=\dfrac{5}{8}\)

\(\dfrac{25}{65}=\dfrac{25:5}{65:5}=\dfrac{5}{13}\)

a) 4 x 76 + 76 x 7
= (4 + 7) x 76
= 11 x 76
= 836
b) 4 x 54 + 54 x 2 + 5 x 54
= (4 + 4 + 5) x 54
= 13 x 54
= 702
c) 37 + 3 x 37 + 5 x 37 + 2 x 37
= 37 x (3 + 5 + 2)
= 37 x 10
= 370

a) 4 x 76 + 76 x 7
= (4 + 7) x 76
= 11 x 76
= 836
b) 4 x 54 + 54 x 2 + 5 x 54
= (4 + 4 + 5) x 54
= 13 x 54
= 702
c) 37 + 3 x 37 + 5 x 37 + 2 x 37
= 37 x (3 + 5 + 2)
= 37 x 10
= 370

a) 4 x 76 + 76 x 7

= (4 + 7) x 76

= 11 x 76

= 836.

b) 4 x 54 + 54 x 2 + 5 x 54

= (4 + 2 + 5) x 54

= 11 x 54

= 594.

c) 37 + 3 x 37 + 5 x 37 + 2 x 37

= 37 x (3 + 5 + 2 + 1)

= 37 x 11

= 407.

sai đề rồi

sai đề

=0:3 thì cũng =0 thôi đề v cũng đố

\(3)1579-(53+1579)-(53) \)

\(=1579-53-1579+53\)

\(=(1579-1579)-(-53+53)\)

\(=0-0\)

\(=0\)

\(4)2001-15+54-2001-54\)

\(=(2001-2001)+(54-54)-15\)

\(=0+0-15\)

\(=0-15\)

\(=-15\)

\(A=\left(1+\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+...+\frac{1}{54}\right).2.3.4.5...54\)

\(\Rightarrow A=\left(1+\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+...+\frac{1}{54}\right).2.3.4.5...11.12...54\)

\(\Rightarrow\hept{\begin{cases}A⋮5\\A⋮11\end{cases}}\)mà \(\left(5,11\right)=1\) nên \(A⋮55\left(đpcm\right)\)