19 + 19 + 12 =
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Chuyển dấu '' - '' của -7/12 sang cho 4/19 thứ 2
=> -4/9 x ( 5/12 + 7/12 ) - 15/19
= -4/9 x 1 - 15/19
= -4/9 - 15/9
= -19/9
d: \(-37\cdot\left(-19\right)+37\left(-19\right)\)
\(=-19\left(-37+37\right)\)
\(=-19\cdot0=0\)
e: \(\left(29-9\right)\cdot\left(-9\right)+\left(-13-7\right)\cdot21\)
\(=20\cdot\left(-9\right)+\left(-20\right)\cdot21\)
\(=-20\left(9+21\right)\)
\(=-20\cdot30=-600\)
h: \(12\cdot\left(-47\right)+12\left(-19\right)+\left(-66\right)\cdot88\)
\(=12\left(-47-19\right)+\left(-66\right)\cdot88\)
\(=\left(-66\right)\cdot12+\left(-66\right)\cdot88\)
\(=-66\left(12+88\right)\)
\(=-66\cdot100=-6600\)
a) \(\dfrac{25}{37}\times\dfrac{18}{29}+\dfrac{18}{29}\times\dfrac{12}{37}\)
\(=\dfrac{18}{29}\times\left(\dfrac{25}{37}+\dfrac{12}{37}\right)\)
\(=\dfrac{18}{29}\times\dfrac{37}{37}\)
\(=\dfrac{18}{29}\times1\)
\(=\dfrac{18}{29}\)
b) \(\dfrac{31}{85}\times\dfrac{11}{19}+\dfrac{31}{85}\times\dfrac{12}{19}-\dfrac{42}{19}\times\dfrac{31}{85}\)
\(=\dfrac{31}{85}\times\left(\dfrac{11}{19}+\dfrac{12}{19}-\dfrac{42}{19}\right)\)
\(=\dfrac{31}{85}\times\dfrac{-19}{19}\)
\(=\dfrac{31}{85}\times-1\)
\(=-\dfrac{31}{85}\)
c) \(\dfrac{16}{53}:\dfrac{17}{9}-\dfrac{16}{53}:\dfrac{17}{8}\)
\(=\dfrac{16}{53}:\left(\dfrac{9}{17}-\dfrac{8}{17}\right)\)
\(=\dfrac{16}{53}:\dfrac{1}{17}\)
\(=\dfrac{16}{901}\)
c) \(\dfrac{1}{5}\times\dfrac{12}{31}\times\dfrac{4}{3}+\dfrac{19}{31}\times\dfrac{4}{15}\)
\(=\dfrac{4}{15}\times\dfrac{12}{31}+\dfrac{19}{31}\times\dfrac{4}{15}\)
\(=\dfrac{4}{15}\times\left(\dfrac{12}{31}+\dfrac{19}{31}\right)\)
\(=\dfrac{4}{15}\times\dfrac{31}{31}\)
\(=\dfrac{4}{15}\times1\)
\(=\dfrac{4}{15}\)
a: =18/29*(25/37+12/37)
=18/29
b: =31/85(11/19+12/19-42/19)
=-31/85
c; =16/53(9/17+8/17)=16/53
d: =4/15(12/31+19/31)=4/15
\(\frac{7}{19}\times\frac{8}{11}+\frac{7}{19}\times\frac{3}{11}+\frac{12}{19}\)
\(=\frac{7}{19}\times\left(\frac{8}{11}+\frac{3}{11}\right)+\frac{12}{19}\)
\(=\frac{7}{19}\times\frac{11}{11}+\frac{12}{19}\)
\(=\frac{7}{19}\times1+\frac{12}{19}\)
\(=\frac{7}{19}+\frac{12}{19}\)
\(=\frac{19}{19}\)
\(=1\)
Chúc bạn học tốt
=50
=5 6