a)  >

b) > 

c) >   

d) < 

a)\(-\dfrac{2}{5}.\dfrac{4}{7}+\dfrac{-3}{5}.\dfrac{2}{7}+\dfrac{-3}{5}\) 

=\(-\dfrac{2}{5}.\dfrac{4}{7}+\dfrac{3}{7}.\dfrac{-2}{5}+\dfrac{-3}{5}\)

=\(-\dfrac{2}{5}.\left(\dfrac{4}{7}+\dfrac{3}{7}\right)+\dfrac{-3}{5}\) 

=\(\dfrac{-2}{5}.1+\dfrac{-3}{5}\) 

=\(-\dfrac{2}{5}+\dfrac{-3}{5}\) 

=\(-\dfrac{5}{5}\) = -1

\(\dfrac{5}{9}.\dfrac{14}{17}+\dfrac{1}{17}.\dfrac{5}{9}+\dfrac{2}{9}+\dfrac{5}{12}\)

=\(\dfrac{5}{9}.\left(\dfrac{14}{17}+\dfrac{1}{17}\right)+\dfrac{2}{9}+\dfrac{5}{12}\) 

=\(\dfrac{5}{9}.\dfrac{15}{17}+\dfrac{2}{9}+\dfrac{5}{12}\) 

=\(\dfrac{25}{51}+\dfrac{2}{9}+\dfrac{5}{12}\)

=\(\dfrac{691}{612}\)

\(-\dfrac{4}{25}:\dfrac{11}{79}+\dfrac{15}{11}:\dfrac{25}{79}\)

=\(-\dfrac{4}{25}.\dfrac{79}{11}+\dfrac{15}{11}.\dfrac{79}{25}\)

=\(-\dfrac{4}{25}.\dfrac{79}{11}+\dfrac{15}{25}.\dfrac{79}{11}\) 

=\(\left(-\dfrac{4}{25}+\dfrac{15}{25}\right).\dfrac{79}{11}\)

=\(\dfrac{11}{25}.\dfrac{79}{11}\) 

=\(\dfrac{79}{25}\)

a)4*x+79*29=79*33

4*x+2291=2607

4*x=2607-2291=316

x=316:4=79

b)83-3*(7+x)=64

3*(7+x)=83- 64=19

7+x=19:3=19/3

x=19/3-7=-2/3

dễ vây mà

thiếu ý D)

117:{[79-3(3^3 -17)]:7+2}

=117:{[79-3(27-17)]:7+2}

=117:{[79-3.10]:7+2}

=117:{[79-30]:7+2}

=117:{49:7+2}

=117:{7+2}

=117:9

=13 

\(\frac{17}{33}.\frac{2}{5}+\frac{3}{5}.\frac{17}{33}-\frac{17}{33}\)

\(=\frac{17}{33}\times\frac{2}{5}+\frac{3}{5}\times\frac{17}{33}-\frac{17}{33}\times1\)

\(=\frac{17}{33}\times\left(\frac{2}{5}+\frac{3}{5}-1\right)\)

\(=\frac{17}{33}\times\left(1-1\right)\)

\(=\frac{17}{33}\times0=\frac{17}{33}\)

 Làm he LÀM đi bạ nó lại  cồn bỏ bỏ

+) \(176+483+24+117\)

\(=\left(176+24\right)+\left(483+117\right)\)

\(=200+600\)

\(=800\)

+) \(239+518+761+482\)

\(=\left(239+761\right)+\left(518+482\right)\)

\(=1000+1000\)

\(=2000\)

+) \(32+33+34+...+78+79+80\)

Số số hạng của dãy là :

\(\left(80-32\right):1+1=49\) (số)

Tổng của dãy là :

\(\frac{\left(80+32\right)\times49}{2}=2744\)

+) \(5\times125\times2\times4\)

\(=\left(5\times2\right)\times\left(125\times4\right)\)

\(=10\times500\)

\(=5000\)

+) \(25\times50\times4\times20\)

\(=\left(25\times4\right)\times\left(50\times20\right)\)

\(=100\times1000\)

\(=100000\)

+) \(17\times32+43\times17+17\times25\)

\(=17\times\left(32+43+25\right)\)

\(=17\times100\)

\(=1700\)

+) \(24\times19+29\times24+18\times24+24\times33+24\)

\(=24\times\left(19+29+18+33+1\right)\)

\(=24\times100\)

\(=2400\)

_Chúc bạn học tốt_

176+483+24+117

=176+24+483+117

=200+600

=800

5*125*2*4

=5*(125*2*4)

=5*1000

=5000