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A=\(\frac{3}{4}.\frac{8}{9}.\frac{15}{16}.........\frac{899}{900}\)
A=\(\frac{1.3}{2.2}.\frac{2.4}{3.3}.\frac{3.5}{4.4}..........\frac{29.31}{30.30}\)
A=\(\frac{1.2.3.......29}{2.3.4.......30}.\frac{3.4.5........31}{2.3.4.......30}\)
A=\(\frac{1}{30}.\frac{2}{31}=\frac{1}{465}\)
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x + 200 + 300 - 100 = 900
x + 400 = 900
x = 900 - 400
x = 500
tk mk nha mk sẽ tk lại
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\(A=\left(1-\frac{1}{4}\right)\left(1-\frac{1}{9}\right)...\left(1-\frac{1}{900}\right)\)
\(A=\frac{3}{4}\cdot\frac{8}{9}\cdot...\cdot\frac{899}{900}\)
\(A=\frac{\left(1\cdot3\right)\left(2\cdot4\right)...\left(29\cdot31\right)}{\left(2\cdot2\right)\left(3\cdot3\right)...\left(30\cdot30\right)}\)
\(A=\frac{\left(1\cdot2\cdot..\cdot29\right)\left(3\cdot4\cdot...\cdot31\right)}{\left(2\cdot3\cdot...\cdot30\right)\left(2\cdot3\cdot...\cdot30\right)}\)
\(A=\frac{1\cdot31}{30\cdot2}\)
\(A=\frac{31}{60}\)
\(\left(-9\right)+9+300+900\)
\(=0+300+900\)
\(=300+900\)
\(=1200\)
k nhé
( - 9 ) + 9 + 300 + 900
= 0 + 300 + 900
= 1200