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a, \(\frac{7.25-49}{7.24+21}\)

\(=\frac{7.25-7.7}{7.24+7.3}=\frac{7\left(25-7\right)}{7\left(24+3\right)}=\frac{18}{27}=\frac{2}{3}\)

b, \(\frac{2.\left(-13\right).9.10}{\left(-3\right).4.\left(-5\right).26}=\frac{2.\left(-13\right).\left(-3\right).\left(-3\right).\left(-5\right).\left(-2\right)}{\left(-3\right).2.2.\left(-5\right).\left(-13\right).\left(-2\right)}\)

\(=\frac{-3}{2}\)

DỄ LẮM !

a) \(\frac{7\cdot25-49}{7\cdot24+21}=\frac{7\cdot25-7\cdot7}{7\cdot24+7\cdot3}=\frac{7\left(25-7\right)}{7\left(24+3\right)}\)

=\(\frac{18}{27}=\frac{2}{3}\)

b) \(\frac{2\cdot\left(-13\right)\cdot9\cdot10}{\left(-3\right)\cdot4\cdot\left(-5\right)\cdot26}=\frac{-1\cdot2\cdot13\cdot3\cdot3\cdot5\cdot2}{1\cdot3\cdot2\cdot2\cdot5\cdot13\cdot2}=-\frac{3}{2}\)

Chúc bn học tốt !

\(a,\frac{2.25-49}{2.24+21}=\frac{2.25-7.7}{7.24+7.3}=\frac{7.\left(25-7\right)}{7.\left(24+3\right)}=\frac{2}{3}\)

\(b,\frac{2.\left(-13\right).9.10}{\left(-3\right).4.\left(-5\right).26}=\frac{2.\left(-1\right).13.3.3.5.2}{1.3.2.2.5.13.2}\frac{-3}{2}\)

a) i)\(\frac{7\cdot25-7\cdot7}{7\cdot24+7\cdot3}=\frac{7\left(25-7\right)}{7\left(24+3\right)}=\frac{18}{27}=\frac{2}{3}\) ii)\(\frac{2\cdot\left(-1\right)\cdot13\cdot\left(-3\right)^2\cdot\left(-2\right)\cdot\left(-5\right)}{\left(-3\right)\cdot2\cdot2\cdot\left(-5\right)\cdot13\cdot2}=\frac{-3}{2}\)

b) i)\(\frac{3}{-4}< 0;\frac{-1}{-4}>0=>\frac{3}{-4}< \frac{-1}{-4}\)   

ii) ta có \(\frac{15}{17}+\frac{2}{17}=1;\frac{25}{27}+\frac{2}{27}=1\)

mà \(\frac{2}{17}>\frac{2}{27}\) =>\(\frac{15}{17}< \frac{25}{27}\)

dug ko v

chắc chắn

\(A=\left(\frac{x}{25+5x}+\frac{5x+50}{x^2+5x}-\frac{10-2x}{x}\right)\div\frac{3x+15}{7}\)

ĐK : \(\hept{\begin{cases}x\ne0\\x\ne-5\end{cases}}\)

\(=\left(\frac{x}{5\left(x+5\right)}+\frac{5\left(x+10\right)}{x\left(x+5\right)}-\frac{2\left(5-x\right)}{x}\right)\div\frac{3\left(x+5\right)}{7}\)

\(=\left(\frac{x^2}{5x\left(x+5\right)}+\frac{5\cdot5\cdot\left(x+10\right)}{5x\left(x+5\right)}-\frac{2\left(5-x\right)\cdot5\left(x+5\right)}{5x\left(x+5\right)}\right)\div\frac{3\left(x+5\right)}{7}\)

\(=\left(\frac{x^2}{5x\left(x+5\right)}+\frac{25x+250}{5x\left(x+5\right)}-\frac{10\left(25-x^2\right)}{5x\left(x+5\right)}\right)\div\frac{3\left(x+5\right)}{7}\)

\(=\left(\frac{x^2+25x+250-250+10x^2}{5x\left(x+5\right)}\right)\div\frac{3\left(x+5\right)}{7}\)

\(=\frac{11x^2+25x}{5x\left(x+5\right)}\times\frac{7}{3\left(x+5\right)}\)

\(=\frac{77x^2+175x}{15x\left(x+5\right)^2}\)

\(=\frac{77x^2+175x}{15x\left(x^2+10x+25\right)}=\frac{77x^2+175x}{15x^3+150x^2+375x}\)

\(=\frac{77x+175}{15x^2+150x+375}\)

\(\frac{-63}{108}\)= \(\frac{-7}{12}\)

\(\frac{-33}{-77}\)= \(\frac{3}{7}\)

\(\frac{-5}{10}\)=\(\frac{-1}{2}\)

\(\frac{14}{63}\)=\(\frac{2}{9}\)

\(\frac{-15}{25}\)=\(\frac{-3}{5}\)

\(\frac{-45}{18}\)=\(\frac{-5}{2}\)

\(\frac{12}{15}\)=\(\frac{4}{5}\)

\(\frac{20}{25}\)=\(\frac{4}{5}\)

\(\frac{31}{12}\):Là phân số tối giản

t.i.c.k nha