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12,5 . (-0,75) . (-0,8) - 0,25 . ( -5,14) . (-4)
= [12,5 . (-0,8)] . (-0,75) - [ 0,25 . (-4)] . (-5,14)
= -10 . ( -0,75) - (-1) . (-5,14)
= 7,5 - 5,14
= 2,36
a, \(2,5:4x=0,5:0,2\)
\(\Rightarrow4x=\dfrac{2,5.0,2}{0,5}\)
\(\Rightarrow4x=1\Rightarrow x=\dfrac{1}{4}\)
b, \(\dfrac{1}{5}x:3=\dfrac{2}{3}:0,5\)
\(\Rightarrow\dfrac{1}{5}x=\dfrac{3.\dfrac{2}{3}}{0,5}\)
\(\Rightarrow\dfrac{1}{5}x=4\Rightarrow x=20\)
c, \(1,25:0,8=\dfrac{3}{8}:0,2x\)
\(\Rightarrow0,2x=\dfrac{0,8.\dfrac{3}{8}}{1,25}\)
\(\Rightarrow0,2x=0,24\Rightarrow x=1,2\)
Chúc bạn học tốt!!
a, \(2,5:4x=0,5:0,2\)
\(2,5:4x=2,5\)
\(4x=2,5:2,5\)
\(4x=1\)
\(x=1:4\)
\(x=\dfrac{1}{4}\)
Vậy .............
b, \(\dfrac{1}{5}x:3=\dfrac{2}{3}\)
\(\dfrac{1}{5}x=\dfrac{2}{3}.3\)
\(\dfrac{1}{5}x=2\)
\(x=2:\dfrac{1}{5}\)
\(x=10\)
Vậy .....
c, \(1,25:0,8=\dfrac{3}{8}:0,2x\)
\(1,5625=\dfrac{3}{8}:0,2x\)
\(0,2x=\dfrac{3}{8}:1,5625\)
\(0,2x=0,24\)
\(x=0,24:0,2\)
\(x=1,2\)
Vậy ...
Ta có :
\(\frac{3}{8}.\frac{58}{3}-\frac{3}{8}.\frac{100}{3}\)
\(=\frac{3}{8}.\left(\frac{58}{3}-\frac{100}{3}\right)\)
\(=\frac{3}{8}.\frac{-42}{3}\)
\(=\frac{-42}{8}=\frac{-21}{4}\)
8/15 + 7/4 + 7/15 + 5/4
= 8/15 + 7/15 + 7/4 +5/4
= ( 8/15 + 7/15) + ( 7/4 + 5/4)
= 15/15 + 12/4
= 1 + 3
=4
789 x 62 - 789 x 8 + 37 x 789 + 789
= 789 x ( 62 - 8 + 37 + 1 )
= 789 x 92
= 72588
~~Cô gái xử nữ~~
Bài làm
\(\frac{\left(1+\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}\right)}{\left(1-\frac{1}{2}+\frac{1}{4}-\frac{1}{8}+\frac{1}{16}\right)}\)
\(=\frac{\left(\frac{2}{2}+\frac{1}{2}+\frac{1}{2^2}+\frac{1}{2^3}+\frac{1}{2^4}\right)}{\left(\frac{2}{2}-\frac{1}{2}+\frac{1}{2^2}-\frac{1}{2^3}+\frac{1}{2^4}\right)}\)
\(=\frac{\frac{1}{2}\left(2+1+\frac{1}{2}+\frac{1}{2^2}+\frac{1}{2^3}\right)}{\frac{1}{2}\left(2-1+\frac{1}{2}-\frac{1}{2^2}+\frac{1}{2^3}\right)}\)
\(=\frac{3+\frac{1}{2}+\frac{1}{2^2}+\frac{1}{2^3}}{1+\frac{1}{2}-\frac{1}{2^2}+\frac{1}{2^3}}\)
\(=\frac{\frac{24}{8}+\frac{4}{8}+\frac{2}{8}+\frac{1}{8}}{\frac{8}{8}+\frac{4}{8}-\frac{2}{8}+\frac{1}{8}}\)
\(=\frac{31}{8}\div\frac{11}{8}\)
\(=\frac{31}{8}\cdot\frac{8}{11}\)
\(=\frac{31}{11}\)
P/S: Trông không thuận tiện lắm :/
\(\frac{4^{19}+8^7}{256^4+32^2}=\frac{\left(2^2\right)^{19}+\left(2^3\right)^7}{\left(2^8\right)^4+\left(2^5\right)^2}=\frac{2^{38}+2^{21}}{2^{32}+2^{10}}=\frac{2^{21}.\left(2^{17}+1\right)}{2^{10}.\left(2^{22}+1\right)}=\frac{2^{11}.\left(2^{17}+1\right)}{2^{22}+1}=\frac{2^{28}+2^{11}}{2^{22}+1}\)
a)
12,5 x 0,42 x 0,8 : 0,7
= (12,5 x 0,8) x (0,42 : 0,7)
= 10 x 0,6
= 6
b
9,83 : 1,25 : 8 + 10,23 : 40 : 0,25
= 9,83 : ( 1,25 x 8 ) + 10,23 : ( 40 x 0,25)
= 9,83 : 10 + 10,23 : 10
= ( 9,83 + 10,23 ) : 10
= 20,06 : 10
= 2,006
Còn thức hả