12.5 . -5/7 + 9 3/4 - 1.5 . 5/7

\(=\frac{5}{7}.\left(-60\right)+\frac{39}{4}-5.\frac{5}{7}\)

\(=\frac{5}{7}.\left[\left(-60\right)-5\right]+\frac{39}{4}\)

\(=\frac{5}{7}.\left(-65\right)+\frac{39}{4}\)

\(=\frac{-325}{7}+\frac{39}{4}=\frac{-1027}{28}\)

học tốt

= 25/2 . -5/7+ 39/4 + -3/2 . 5/7 = -125/14 + 39/4 + -15/14 = ( -125/14 + -15/14 ) + 39/4 = -10 + 39/4 = -1/4

\(=\dfrac{5}{7}\cdot\dfrac{3}{11}-\dfrac{5}{7}\cdot\dfrac{9}{11}+\dfrac{5}{7}=\dfrac{5}{7}\left(\dfrac{3}{11}-\dfrac{9}{11}+1\right)=\dfrac{5}{7}\cdot\dfrac{5}{11}=\dfrac{25}{77}\)

\(\dfrac{5}{7} . \dfrac{3}{11} + \dfrac{-5}{7} . \dfrac{9}{11} + 1 . \dfrac{5}{7} \) 

\(= \dfrac{5}{7} . \dfrac{3}{11} - \dfrac{5}{7} . \dfrac{9}{11} + 1 .\dfrac{5}{7} \)

\(= \dfrac{5}{7} . ( \dfrac{3}{11} - \dfrac{9}{11} - 1 )\) 

\(= \dfrac{5}{7} . \dfrac{5}{11} \)

\(= \dfrac{25}{77} \) 

a) Đặt: A = \(\frac{5.7^{12}}{7^{10}.5^{10}}=\frac{5.7^2.7^{10}}{7^{10}.5^{10}}=\frac{7^2}{5^9}\)

b) Đặt: B = \(\frac{5^8.7^{12}-5^9.7^{11}}{7^{11}.5^{10}+7^{12}.5^{11}}=\frac{5^8.7.7^{11}-5.5^8.7^{11}}{7^{11}.5^{10}+7.7^{11}.5.5^{10}}\\ =\frac{5^8.7^{11}.\left(7-5\right)}{7^{11}.5^{10}.\left(1+7.5\right)}=\frac{2}{5^2.36}=\frac{2}{25.36}=\frac{1}{450}\)

a)\(\frac{5.7^{12}}{7^{10}.5^{10}}=\frac{5.7^{10}.7^2}{7^{10}.5.5^9}=\frac{7^2}{5^9}\)

a) (5² + 1) - 9.3

= 26 - 9.3

= 16.7

b) 80 - (4.5² - 3.2³)

= 80 - (20.25 - 32.768)

= 80 - (-12.518)

= 92.518

c)[(-18) + (-7)] -15

= -25 - 15

= -40

d) (-219) - (-229) + 12.5

= 10 + 12.5

= 22.5

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