A=1/3^2+1/4^2+1/5^2+1/6^2+...+1/100^2<1/2-1/3+1/3-1/4+...+1/99-1/100
=>A<1/2-1/100<1/2
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Ôn tập chương II
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Tìm x :a) 0,75x - x + 1dfrac{1}{4}x 20%b) dfrac{1}{3}- x dfrac{-1}{2}+dfrac{2}{3}c)dfrac{x-1}{45}dfrac{-3}{5}.dfrac{2}{6}d) left(dfrac{2x}{5}-1right):(-5)dfrac{1}{7}Mình k vội nên có gì tính kĩ giùm mình nkaa 3 . Cơ mak giảng từng bước tính cho mình luôn cũm đựt ấy :) . Thankiuu nkiềuu nkaaa
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Tìm x :
a) 0,75x - x + \(1\dfrac{1}{4}\)x = 20%
b) \(\dfrac{1}{3}\)- x =\(\dfrac{-1}{2}\)+\(\dfrac{2}{3}\)
c)\(\dfrac{x-1}{45}\)=\(\dfrac{-3}{5}\).\(\dfrac{2}{6}\)
d) \(\left(\dfrac{2x}{5}-1\right)\):(-5)=\(\dfrac{1}{7}\)
Mình k vội nên có gì tính kĩ giùm mình nkaa <3 . Cơ mak giảng từng bước tính cho mình luôn cũm đựt ấy :) . Thankiuu nkiềuu nkaaa
Tìm x:a) (2x - 3)(6 - 2x) 0b) 5dfrac{4}{7}:x13 c) 2x - dfrac{3}{7} 6dfrac{2}{7}d) dfrac{x}{5} + dfrac{1}{2} dfrac{6}{10}e) dfrac{x+3}{15}dfrac{1}{3}f) dfrac{x-12}{4}dfrac{1}{2}g) 2dfrac{1}{4}.left(x-7dfrac{1}{3}right)1,5h) left(4,5-2xright).1dfrac{4}{7}dfrac{11}{14}i) dfrac{2}{3}left(x-25%right)dfrac{1}{6}k) dfrac{3}{2}x-1dfrac{1}{2}x-dfrac{3}{4}
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Tìm x:
a) (2x - 3)(6 - 2x) = 0
b) \(5\dfrac{4}{7}:x=13\)
c) 2x - \(\dfrac{3}{7}\) = \(6\dfrac{2}{7}\)
d) \(\dfrac{x}{5}\) + \(\dfrac{1}{2}\) = \(\dfrac{6}{10}\)
e) \(\dfrac{x+3}{15}=\dfrac{1}{3}\)
f) \(\dfrac{x-12}{4}=\dfrac{1}{2}\)
g) \(2\dfrac{1}{4}\).\(\left(x-7\dfrac{1}{3}\right)=1,5\)
h) \(\left(4,5-2x\right).1\dfrac{4}{7}=\dfrac{11}{14}\)
i) \(\dfrac{2}{3}\left(x-25\%\right)=\dfrac{1}{6}\)
k) \(\dfrac{3}{2}x-1\dfrac{1}{2}=x-\dfrac{3}{4}\)
26 tháng 4 2021 lúc 14:13
câu 1: (x+dfrac{1}{2}).(dfrac{2}{3}-2x)0câu 2: (3x-10)(-dfrac{1}{2}x+5)0câu 3: dfrac{1}{3}x+dfrac{53}{4}dfrac{65}{4}câu 4: dfrac{2}{3}x-dfrac{4}{9}dfrac{2}{9}câu 5: dfrac{1}{1.2}+dfrac{1}{2.3}+...+dfrac{1}{xleft(x+1right)}dfrac{2010}{2011}
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câu 1: (x+\(\dfrac{1}{2}\)).(\(\dfrac{2}{3}\)-2x)=0
câu 2: (3x-10)(-\(\dfrac{1}{2}\)x+5)=0
câu 3: \(\dfrac{1}{3}\)x+\(\dfrac{53}{4}\)=\(\dfrac{65}{4}\)
câu 4: \(\dfrac{2}{3}\)x-\(\dfrac{4}{9}\)=\(\dfrac{2}{9}\)
câu 5: \(\dfrac{1}{1.2}\)+\(\dfrac{1}{2.3}\)+...+\(\dfrac{1}{x\left(x+1\right)}\)=\(\dfrac{2010}{2011}\)
\(\dfrac{-1}{2}-\left(\dfrac{3}{2}+x\right)=-2\)
ai giúp mình nhanh với mình cần gấp
\(\dfrac{-5}{7}\)+\(\dfrac{3}{4}\)+\(\dfrac{-2}{10}\)+\(\dfrac{-2}{7}\)+\(\dfrac{1}{4}\)
Thực hiện phép tính ( tính nhanh nếu có thể )
a)dfrac{4}{11}.dfrac{2}{5}+dfrac{4}{5}.dfrac{9}{11}+dfrac{5}{6}
b)2dfrac{1}{2}.60%-left(dfrac{3}{7}+0,15right):dfrac{3}{10}
c)15dfrac{3}{13}-left(3dfrac{4}{7}+8dfrac{3}{13}right)
d)dfrac{-7}{9}.dfrac{4}{11}+dfrac{-7}{9}.dfrac{7}{11}+5dfrac{7}{9}
e)50%.1dfrac{1}{3}.10.dfrac{7}{35}.0,75
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Thực hiện phép tính ( tính nhanh nếu có thể )
a)\(\dfrac{4}{11}.\dfrac{2}{5}+\dfrac{4}{5}.\dfrac{9}{11}+\dfrac{5}{6}\)
b)\(2\dfrac{1}{2}.60\%-\left(\dfrac{3}{7}+0,15\right):\dfrac{3}{10}\)
c)\(15\dfrac{3}{13}-\left(3\dfrac{4}{7}+8\dfrac{3}{13}\right)\)
d)\(\dfrac{-7}{9}.\dfrac{4}{11}+\dfrac{-7}{9}.\dfrac{7}{11}+5\dfrac{7}{9}\)
e)\(50\%.1\dfrac{1}{3}.10.\dfrac{7}{35}.0,75\)
30%+\(\dfrac{2}{3}\):\(\dfrac{5}{6}\)-0,6*1\(\dfrac{2}{3}\)
Tính nhanh :
Q = \(\left(\dfrac{1}{99}+\dfrac{12}{999}+\dfrac{123}{9999}\right).\left(\dfrac{1}{2}-\dfrac{1}{3}-\dfrac{1}{6}\right)\)
a, A = \(\dfrac{-7}{8}.\dfrac{5}{9}-\dfrac{4}{9}.\dfrac{7}{8}+5\dfrac{7}{8}\)
b, B = 0,25.\(1\dfrac{3}{5}.\left(\dfrac{5}{4}\right)^2:\left(\dfrac{-4}{7}\right)\)