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\(=\dfrac{11}{4}\cdot\dfrac{2}{5}-\dfrac{8}{5}\cdot\dfrac{11}{4}+\dfrac{-6}{5}\cdot\dfrac{11}{4}\)
=11/4x(-12/5)=-132/20=-33/5
A=\(\frac{1}{2}+\frac{1}{3}+0,4+\frac{5}{7}+\frac{1}{6}-\frac{4}{35}\)
\(A=\frac{3}{6}+\frac{2}{6}+\frac{2}{5}+\frac{5}{7}+\frac{1}{6}-\frac{4}{35}\)
\(A=\left(\frac{3}{6}+\frac{2}{6}+\frac{1}{6}\right)+\left(\frac{2}{5}+\frac{5}{7}-\frac{4}{35}\right)\)
\(A=1+\left(\frac{14}{35}+\frac{25}{35}-\frac{4}{35}\right)\)
\(A=1+1\)
\(A=2\)
\(A=\dfrac{2}{3}+\dfrac{3}{4}.\left(\dfrac{-4}{9}\right)\)
\(A=\dfrac{2}{3}+\dfrac{-1}{3}\)
\(A=\dfrac{1}{3}\)
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( *Xem lại câu B nha bạn )
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\(C=\left(\dfrac{3}{4}-0,2\right).\left(0,4-\dfrac{4}{5}\right)\)
\(C=\left(\dfrac{3}{4}-\dfrac{1}{5}\right).\left(\dfrac{2}{5}-\dfrac{4}{5}\right)\)
\(C=\dfrac{11}{20}.\dfrac{-2}{5}\)
\(C=\dfrac{-11}{50}\)
d)\(\frac{2}{3.5}+\frac{2}{5.7}+....+\frac{2}{97.99}\)
\(=\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+....+\frac{1}{97}-\frac{1}{99}\)
\(=\frac{1}{3}-\frac{1}{99}\)
\(=\frac{32}{99}\)
a) 11/4x(-0,4)x-1,6x11/4
= -1,1 x-1,6x11/4
= 1,76x11/4
= 4,48
b) 6/19x-7/11+6/19x-4/19x-4/11+13/19
= -42/209+96/3971+13/19
= -702/3971+13/19
= 2015/3971
c) 2/5x3/7+-3/7x3/5+3/7
= 3/7x(2/5+3/5+1)
= 3/7x(1+1)
= 3/7x2
= 6/7
d) 2/3x5+2x5/7+2/7x9+....+2/97x99
= 1/3-1/5+1/5-1/7+1/7-1/9+......+1/97-1/99
= 1/3-1/99
= 32/99
Đề sai rùi , bn ktra lại nhen
`2+3.(2.4)=0,4`
Đề là tìm `x` thì có thiếu đề ko v bn ?