Có: \(\dfrac{7}{6}\times\dfrac{1}{2}+\dfrac{7}{6}\times\dfrac{3}{4}+\dfrac{7}{6}+\dfrac{15}{4}\)

\(=\dfrac{7}{6}\times\left(\dfrac{1}{2}+\dfrac{3}{4}+1\right)+\dfrac{15}{4}\)

\(=\dfrac{7}{6}\times\dfrac{9}{4}+\dfrac{15}{4}\)

\(=\dfrac{63}{24}+\dfrac{90}{24}=\dfrac{51}{8}\)

7/6 × 1/2 + 7/6 × 3/4 + 7/6 × 15/4

= 7/6 × (1/2 + 3/4 + 15/4)

= 7/4 × (2/4 + 3/4 + 15/4)

= 7/4 × 5

= 35/4

\(\dfrac{2}{5}+\dfrac{4}{5}:4=\dfrac{2}{5}+\dfrac{1}{5}=\dfrac{3}{5}\)

\(\dfrac{3}{8}\times\dfrac{7}{4}-\dfrac{3}{8}=\dfrac{3}{8}\left(\dfrac{7}{4}-1\right)=\dfrac{3}{8}\times\dfrac{3}{4}=\dfrac{9}{32}\)

\(\dfrac{6}{5}-3:\dfrac{15}{4}=\dfrac{6}{5}-\dfrac{4}{5}=\dfrac{2}{5}\)

\(=\dfrac{2}{5}+\dfrac{4}{5}\times\dfrac{1}{4}\\ =\dfrac{2}{5}+\dfrac{1}{5}\\ =\dfrac{3}{5}\\ \\ =\dfrac{3}{8}\times\dfrac{7}{4}-\dfrac{3}{8}\times1\\ =\dfrac{3}{8}\times\left(\dfrac{7}{4}-1\right)\\ =\dfrac{3}{8}\times\dfrac{3}{4}\\ =\dfrac{9}{32}\\\\ =\dfrac{6}{5}-3\times\dfrac{4}{15}\\ =\dfrac{6}{5}-\dfrac{4}{5}\\ =\dfrac{2}{5}\)

\(\dfrac{2}{5}+\dfrac{4}{5}:4=\dfrac{2}{5}+\dfrac{1}{5}=\dfrac{3}{5}\\ \dfrac{3}{8}\times\dfrac{7}{4}-\dfrac{3}{8}=\dfrac{3}{8}\times\dfrac{7}{4}-\dfrac{3}{8}\times1=\dfrac{3}{8}\times\left(\dfrac{7}{4}-1\right)=\dfrac{3}{8}\times\dfrac{3}{4}=\dfrac{9}{32}\\ \dfrac{6}{5}-3:\dfrac{15}{4}=\dfrac{6}{5}-\dfrac{4}{5}=\dfrac{2}{5}\)

M=(-4/1.5)-(4/5.9)-(4/n-4).n

=-1(4/1.5+4/5.9+4n/n-4)

=-1(1/1-1/5+1/5-1/9+4n/n-4)

=-1(1-1/9+4n/n-4)

=-1(8/9+4n/n-4)

=-8/9+(-4n/n-4)

=(-8n+32-36n)/9(n-4)

=(-44n+32)/9(n-4)

mình thử máy tính kq ra vậy có j ko hiểu thì cứ hỏi nhé ^^ chúc bn học tốt ^^

194/175

co ai giai giup  minh voi please!

ban oi cu the

3A=5(3/1*4+3/4*7+...+3/91*94)

3A=5(1-1/4+1/4-1/7+...+1/91-1/94)

3A=5(1-1/94)

3A=5.93/94

A=(5.93/94):3

A=155/94

a,{ [ - 2/3 + 3/7 ] + [ -1/3 + 4/7 ] } ; 4/5 =

   (   -3/3 + 7/7 ) : 4/5 = 

(-1+1 ) :4/5 = 

0 :4/5 = 0

-5/21 : 4 / 5 + 5/21 : 4/5 = -25 / 84 + 25 / 84 = 0 

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