Có: \(P=\left\{1;4;9;16;25;36;49;64;81\right\}\)

Ta thấy: \(1=1^2\)

\(4=2^2\)

\(9=3^2\)

\(.......\)

\(81=9^2\)

\(\Rightarrow P=\left\{x|x\in N=k^2\left(k\in\left\{1;2;3;...;9\right\}\right)\right\}\)

P={x\(\in\)N\(|\) \(1\le x\le9\) và \(x^2\)}

P = \(\left\{x\in N,x=k^2,k< 10\right\}\)

a) \(-\dfrac{9}{18}+\dfrac{-18}{27}=\dfrac{-1}{2}+\dfrac{-2}{3}=\dfrac{-3}{6}+\dfrac{-4}{6}=\dfrac{-7}{6}\)

b) \(\dfrac{12}{16}-\dfrac{10}{25}=\dfrac{3}{4}-\dfrac{2}{5}=\dfrac{15}{20}-\dfrac{8}{20}=\dfrac{7}{20}\)

c) \(-2+\dfrac{-2}{3}=\dfrac{-6}{3}+\dfrac{-2}{3}=\dfrac{-8}{3}\)

d) \(\dfrac{2}{5}-1=\dfrac{2}{5}-\dfrac{5}{5}=\dfrac{-3}{5}\)

\(#NqHahh\)

2.31.12+4.6.42+8.27.3=24.31+24.42+24.27=24.(31+42+27)=24.100=2400

34,03 x 28,64 + 34,03 x 71,46 + 27,05

= 34,03 x (28,64+71,46) + 27,05

= 34,03 x 100 + 27,05

= 3403 + 27,05

= 3430,05

34,03 . 28,54 + 34,03 . 71,46 + 27,05

= 34,03( 28,54 + 71,46 ) + 27,05

= 34,03 . 100 + 27,05

= 3403 + 27,05

= 3430,05

34,03.28,54+34,03.71,46+27,05

=34,03.(28,54+71,46)+27,05

=34,03.100+27,05

=3403+27,05

=3430,05

116-(115-99)

= 116 - 115 + 99

= 1 + 99

= 100

HT và $$$

\(\left(324.359+24\right):\left(137.10+357.322\right)\)

\(=\left(116316+24\right):\left(1370+114954\right)\)

\(=116340:116324\)

\(=\dfrac{29085}{29081}\)