\(\left|1,9\right|+19201-\left|1932\right|\)
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\(\left(1-\frac{1}{1931}\right)\left(1-\frac{1}{1932}\right)......\left(1-\frac{1}{2012}\right)\)
\(=\frac{1930}{1931}\cdot\frac{1931}{1932}\cdot...\cdot\frac{2011}{2012}\)
\(=\frac{1930\cdot1931\cdot...\cdot2011}{1931\cdot1932\cdot...\cdot2012}=\frac{1930}{2012}=\frac{965}{1006}\)
\(\left(1-\frac{1}{1931}\right)\times\left(1-\frac{1}{1932}\right)\times\left(1-\frac{1}{1933}\right)\times...\times\left(1-\frac{1}{2012}\right)\)
\(=\left(\frac{1931}{1931}-\frac{1}{1931}\right)\times\left(\frac{1932}{1932}-\frac{1}{1932}\right)\times\left(\frac{1933}{1933}-\frac{1}{1933}\right)\times...\times\left(\frac{2012}{2012}-\frac{1}{2012}\right)\)
\(=\frac{1930}{1931}\times\frac{1931}{1932}\times\frac{1932}{1933}\times...\times\frac{2011}{2012}\)
\(=\frac{1930\times1931\times1932\times...\times2011}{1931\times1932\times1933\times...\times2012}\)
\(=\frac{1930}{2012}=\frac{965}{1006}\)
\(K=\left(\dfrac{10}{3}\cdot\dfrac{19}{10}+\dfrac{19}{2}:\dfrac{13}{3}\right)\cdot\dfrac{2}{3}\)
\(=\dfrac{665}{117}\)
\(K=\left(\dfrac{10}{3}\cdot\dfrac{19}{10}+\dfrac{19}{2}:\dfrac{13}{3}\right)\cdot\left(\dfrac{62}{75}-\dfrac{12}{25}\right)=\left(\dfrac{19}{3}+\dfrac{57}{26}\right)\cdot\dfrac{2}{3}=\dfrac{665}{78}\cdot\dfrac{2}{3}=\dfrac{665}{117}\)
a)
\(\left(-3,8\right)+\left[\left(-5,7\right)+\left(+3,8\right)\right]\\ =\left(-3,8\right)+\left(-5,7\right)+3,8\\ =\left[\left(-3,8\right)+3,8\right]+\left(-5,7\right)\\ =0+\left(-5,7\right)\\ =-5,7\)
b)
\(\left(+31,4\right)+\left[\left(+6,4\right)+\left(-18\right)\right]\\ =31,4+6,4-18\\ =37,8-18\\ =19,8\)
c)
\(\left[\left(-9,6\right)+\left(+4,5\right)\right]+\left[\left(+9,6\right)+\left(-1,5\right)\right]\\ =\left(-9,6\right)+4,5+9,6-1,5\\ =\left[\left(-9,6\right)+9,6\right]+\left[4,5-1,5\right]\\ =0+3\\ =3\)
d)
\(\left[\left(-4,9\right)+\left(-37,8\right)\right]+\left[\left(+1,9\right)+\left(+2,8\right)\right]\\ =\left(-4,9\right)-37,8+1,9+2,8\\ =\left[\left(-4,9+1,9\right)\right]-\left[\left(37,8-2,8\right)\right]\\ =\left(-3\right)-35\\ =-38\)
a)(-3,8)+[(-5,7)+3,8]
=(-3,8)+(-5,7)+3,8
=(-3,8)+3,8+(-5,7)
=0+(-5,7)
=-5,7
1a, (-3,8) + [ (-5,7)+3,8]
= (-3,8+3,8) -5,7
= -5,7
b, 31,4 +[6,4 +(-18)]
= 31,4 - 11,6
= 19,8
c,[(9,6 )+4,5 ] +[9,6 +(-1,5)]
= 9,6 +9,6 +(4,5-1,5)
= 19,2 +3
=22,2
d, [ (-4,9) + (-7,8)] +[1,9+2,8]
= (-4,9 +1,9)+ (-7,8+2,8)
= -3 -5
=-8
e, (3,1-2,5)-(-2,5+3,1)
= (3,1-3,1)+(2,5-2,5)
=0
f, (5,3 -2,8 )- (4+5,3)
= (5,3-5,3) -2,8-4
= -6,8
g, -(251,3 +281 )+ 3,251 -(1-281)
= -251,3-281+3,251 -1+281
= (-281+281) -251,3 +3,251 -1
= -249,049
h,-(3/54+3/4)-(-3/4 +2/5)
= -3/54-3/4 +3/4 +2/5
=(-3/4+3/4) -3/54 +2/5
=123/270
chúc bạn học tốt
\(x< -0,8\Rightarrow x+0,8< 0\Rightarrow\left|x+0,8\right|=-\left(x+0,8\right)\)
\(x< -0,8\Rightarrow x< 25\Rightarrow x-25< 0\Rightarrow\left|x-25\right|=25-x\)
\(\Rightarrow A=\left|x+0,8\right|-\left|x-25\right|+1,9=-\left(x+0,8\right)-\left(25-x\right)+1,9\)
\(=-x-0,8-25+x+1,9=-0,8-25+1,9=-23,9\)
\(A=-5,13:\left(5\dfrac{5}{28}-1\dfrac{8}{9}.1,25+1\dfrac{16}{63}\right)\)
\(=-5,13:\left(\dfrac{145}{28}-\dfrac{17}{9}.\dfrac{125}{100}+\dfrac{79}{63}\right)\)
\(=-5,13:\left(\dfrac{145}{28}-\dfrac{17}{9}.\dfrac{5}{4}+\dfrac{79}{63}\right)\)
\(=-5,13:\left(\dfrac{145}{28}-\dfrac{85}{36}+\dfrac{79}{63}\right)\)
\(=-5,13:\dfrac{57}{14}=-5,13:\dfrac{15}{57}\)
\(=\dfrac{-71,82}{57}=1,26\)
Vậy \(A=1,26\)
\(B=\left(3\dfrac{1}{3}.1,9+19,5:4\dfrac{1}{3}\right).\left(\dfrac{62}{75}-\dfrac{4}{25}\right)\)
\(=\left(\dfrac{10}{3}.1,9+19,5:\dfrac{13}{3}\right).\left(\dfrac{62-12}{75}\right)\)
\(=\left(\dfrac{19}{3}+\dfrac{58,5}{13}\right).\dfrac{50}{75}\)
\(=\left(\dfrac{19}{3}+4,5\right).\dfrac{2}{3}\)
\(=\dfrac{32,5}{3}.\dfrac{2}{3}=\dfrac{65}{9}=7\dfrac{2}{9}\)
Vậy \(B=7\dfrac{2}{9}\)
\(|1,9|+19201-|1932|\)
\(=1,9+\left(19201-1932\right)\)
\(=1,9+17269\)
\(=17270,9\)
Hk tốt
Ta có:|1,9|+19201-|1982|
= 1,9+19201 -1982
=17219+1,9
=17220,9