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\(...=\dfrac{152}{10}-\dfrac{15}{9}+\dfrac{48}{10}-\dfrac{4}{19}=\dfrac{76}{5}-\dfrac{5}{3}+\dfrac{24}{5}-\dfrac{4}{19}\)
\(=\dfrac{76}{5}-\dfrac{5}{3}+\dfrac{24}{5}-\dfrac{4}{19}=\dfrac{76}{5}+\dfrac{24}{5}-\dfrac{5}{3}-\dfrac{4}{19}\)
\(=\dfrac{100}{5}-\dfrac{5}{3}-\dfrac{4}{19}=20-\dfrac{5}{3}-\dfrac{4}{19}=\dfrac{20.57-5.19-4.3}{57}=\dfrac{1033}{57}\)
a) \(\dfrac{-15}{-2023}=\dfrac{15}{2023}>0\)
\(\dfrac{3}{-4}< 0\)
\(\Rightarrow\dfrac{-15}{-2023}>\dfrac{3}{-4}\)
b) \(\dfrac{2014}{-2015}< 0\)
\(\dfrac{-5}{-7}=\dfrac{5}{7}>0\)
\(\Rightarrow\dfrac{2014}{-2015}< \dfrac{-5}{-7}\)
c) \(\dfrac{-4162}{3976}< 0\)
\(\dfrac{1}{2}>0\)
\(\Rightarrow\dfrac{-4162}{3976}< \dfrac{1}{2}\)
d) \(\dfrac{-2401}{7693}< 0\)
\(\dfrac{-4}{-7}=\dfrac{4}{7}>0\)
\(\Rightarrow\dfrac{-2401}{7693}< \dfrac{4}{7}\)
a: \(\dfrac{-15}{-2023}=\dfrac{15}{2023}>0\)
\(\dfrac{3}{-4}< 0\)
Do đó: \(\dfrac{-15}{-2023}>\dfrac{3}{-4}\)
b: \(\dfrac{2014}{-2015}< 0\)
\(\dfrac{-5}{-7}=\dfrac{5}{7}>0\)
Do đó: \(\dfrac{2014}{-2015}< \dfrac{-5}{-7}\)
c: \(-\dfrac{4162}{3976}< 0\)
\(0< \dfrac{1}{2}\)
Do đó: \(-\dfrac{4162}{3976}< \dfrac{1}{2}\)
d: \(\dfrac{-2401}{7693}< 0\)
\(0< \dfrac{4}{7}=\dfrac{-4}{-7}\)
Do đó: \(-\dfrac{2401}{7693}< \dfrac{-4}{-7}\)
e: -17<-4
=>\(\dfrac{-17}{2019}< \dfrac{-4}{2019}\)
=>\(\dfrac{17}{-2019}< \dfrac{-4}{2019}\)
g: \(\dfrac{-15}{-43}=\dfrac{15}{43}\)
mà 15>7
nên \(\dfrac{-15}{-43}=\dfrac{15}{43}>\dfrac{7}{43}\)
h: \(\dfrac{-15}{60}=\dfrac{-15\cdot3}{60\cdot3}=\dfrac{-45}{180}\)
\(\dfrac{-20}{45}=\dfrac{-20\cdot4}{45\cdot4}=\dfrac{-80}{180}\)
Ta có: -45>-80
=>\(-\dfrac{45}{180}>-\dfrac{80}{180}\)
=>\(-\dfrac{15}{60}>-\dfrac{20}{45}\)
k: \(\dfrac{11}{45}>0\)
\(0>-\dfrac{14}{30}\)
Do đó: \(\dfrac{11}{45}>-\dfrac{14}{30}\)
m: \(-\dfrac{17}{15}< -\dfrac{15}{15}=-1\)
\(-1< -\dfrac{5}{18}=\dfrac{5}{-18}\)
Do đó: \(\dfrac{-17}{15}< \dfrac{5}{-18}\)
n: \(-\dfrac{14}{42}< 0\)
\(0< \dfrac{-56}{-28}\)
Do đó: \(\dfrac{-14}{42}< \dfrac{-56}{-28}\)
a: 12h: 0 độ
10h: 60 đọ
6h: 180 độ
5h: 150 độ
b:
a: góc nhọn: góc yMz; góc tMz
b: góc vuông: góc yMt, góc xMt
c: góc tù: góc xMz
d: góc bẹt: góc xMy
b) Diện tích hình tròn là: \(4^2.3,14=50,24\left(cm^2\right).\)
Chu vi hình tròn là: \(4.2.3,14=25,12\left(cm\right).\)
a) Ta có hình vẽ sau:
b) Diện tích hình tròn là:
4 . 4 . 3,14 = 50,24 (cm2)
Chu vi hình tròn là:
4 . 2 . 3,14 = 25,12 (cm)
1) \(5\cdot2^2-18:3=5\cdot4-6=20-6=14\)
2) \(29\cdot75+25\cdot29-250=29\cdot\left(75+25\right)-250=29\cdot100-250=2900-250=2650\)
3) \(561+216+139+154=\left(561+139\right)+\left(216+154\right)=700+370=1070\)
4) \(91:\left\{350:\left[450-\left(4\cdot5^3-2^2\cdot25\right)\right]\right\}=91:\left\{350:\left[450-\left(4\cdot125-4\cdot25\right)\right]\right\}\)
\(=91:\left[350:\left(450-400\right)\right]=91:\left(350:50\right)=91:7=13\)
Tham khảo:
Ta có các phân số 1/11 ; 1/12 ; 1/13 ; 1/14 ; 1/15 ; 1/16 ; 1/17 ; 1/18 ; 1/19 đều lớn hơn 1/20
Do đó : 1/11 + 1/12 + 1/13 + 1/14 + 1/15 + 1/16 + 1/17 + 1/18 + 1/19 + 1/20 > 1/20 + 1/20 + ;...+ 1/20 ( có 10 phân số 1/20 )
1/11 + 1/12 + 1/13 + 1/14 + 1/15 + 1 /16 + 1/17 + 1/18 + 1/19 + 1/20 > 10/20
1/11 + 1/12 + 1/13 + 1/14 + 1/15 + 1 /16 + 1/17 + 1/18 + 1/19 + 1/20 > 1/2
Vậy : S > 1/2
Ta có: \(\dfrac{1}{2}=\dfrac{10}{20}=\dfrac{1}{20}+\dfrac{1}{20}+...+\dfrac{1}{20}\) ( Có 10 số \(\dfrac{1}{20}\) )
Mà \(\dfrac{1}{20}< \dfrac{1}{19}:\dfrac{1}{20}< \dfrac{1}{18}:...:\dfrac{1}{20}< \dfrac{1}{11}\)
\(\Rightarrow\dfrac{1}{20}+\dfrac{1}{20}+...+\dfrac{1}{20}< \dfrac{1}{20}+\dfrac{1}{19}+\dfrac{1}{18}+...+\dfrac{1}{11}\)
\(\Rightarrow A=B\)
Đáp án là -3!
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