\(a,\dfrac{2}{3}.\dfrac{5}{4}-\dfrac{3}{4}.\dfrac{2}{3}=\dfrac{2}{3}.\left(\dfrac{5}{4}-\dfrac{3}{4}\right)=\dfrac{2}{3}.\dfrac{2}{4}=\dfrac{1}{3}\)

\(b,2.\left(\dfrac{-3}{2}\right)-\dfrac{7}{2}=-6.\dfrac{1}{2}-7.\dfrac{1}{2}=\left(-6-7\right).\dfrac{1}{2}=-13.\dfrac{1}{2}=\dfrac{-13}{2}\)

\(c,-\dfrac{3}{4}.5\dfrac{3}{13}-0,75.\dfrac{36}{13}=-\dfrac{3}{4}.\left(\dfrac{68}{13}-\dfrac{36}{13}\right)=-\dfrac{3}{4}.\dfrac{32}{13}=-\dfrac{24}{13}\)

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

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

\(=\dfrac{2}{3}.\dfrac{2}{4}\)

\(=\dfrac{2}{3}.\dfrac{1}{2}\)

\(=\dfrac{1}{3}\)

b) \(2.\left(\dfrac{-3}{2}\right)^2-\dfrac{7}{2}\)

\(=2.\dfrac{9}{4}-\dfrac{7}{2}\)

\(=\dfrac{9}{2}-\dfrac{7}{2}\)

\(=\dfrac{2}{2}=1\)

c) \(-\dfrac{3}{4}.5\dfrac{3}{13}-0,75.\dfrac{36}{13}\)

\(=-\dfrac{3}{4}.\dfrac{68}{13}-\dfrac{3}{4}.\dfrac{36}{13}\)

\(=\dfrac{3}{4}.\dfrac{-68}{13}-\dfrac{3}{4}.\dfrac{36}{13}\)

\(=\dfrac{3}{4}.\left(\dfrac{-68}{13}-\dfrac{36}{13}\right)\)

\(=\dfrac{3}{4}.\dfrac{-104}{13}\)

\(=\dfrac{3}{4}.\left(-8\right)\)

\(=-6\)

NGHĨA LÀ :

\(\frac{3^2}{0,375^2}\)Ý HẢ

Ta có:

\(\frac{3^2}{0,375^2}\)

=\(\frac{9}{0.140625}\)

=64

Ta có : P = 3² + 6² + 9² + .... + 30²

= 3²(1² + 2² + 3² + .... + 10²)

= 9.385 

= 3465

Vậy P = 3465

P = 3² + 6² + 9² + ... + 30²

= ( 1.3 )² + ( 2.3 )² + ( 3.3 )² + ... + ( 10.3 )²

= 1².3² + 2².3² + 3².3² + ... + 10².3²

= 3²( 1² + 2² + 3² + ... + 10² )

= 9.385 = 3465

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mũ 2 tui ko bt

toi ko co the bt day nh vau ko dau