Bài1. (4điểm) Thực hiện phép tính:
a) \(A=\dfrac{3}{5}+6\dfrac{5}{6}\left(11\dfrac{5}{20}-9\dfrac{1}{4}\right):8\dfrac{1}{3}\)
b) \(B=\dfrac{-1}{2}+\dfrac{-1}{6}+\dfrac{-1}{12}+\dfrac{-1}{20}+\dfrac{-1}{30}+\dfrac{-1}{42}+\dfrac{-1}{56}+\dfrac{-1}{72}+\dfrac{-1}{90}\)
Tính các tích sau:
a) \(P=\dfrac{3}{4}\cdot\dfrac{8}{9}\cdot\dfrac{15}{16}\cdot...\cdot\dfrac{99}{100}\)
b) \(Q=\left(\dfrac{1}{9}-1\right)\left(\dfrac{2}{9}-1\right)\left(\dfrac{3}{9}-1\right)...\left(\dfrac{19}{9}-1\right)\)
\(\left(1-\dfrac{1}{2}\right)\left(1-\dfrac{1}{3}\right)\left(1-\dfrac{1}{4}\right)\left(1-\dfrac{1}{5}\right)\left(1-\dfrac{1}{6}\right)\left(1-\dfrac{1}{7}\right)\left(1-\dfrac{1}{8}\right)\left(1-\dfrac{1}{9}\right)\left(1-\dfrac{1}{10}\right)\)
Bài 1: Tính:
a) 10,(3) + 0,(4) - 8,(6)
b) \(\dfrac{0,8:\left(\dfrac{4}{5}.1,25\right)}{0,64-\dfrac{1}{25}}+\dfrac{\left(1,08-\dfrac{2}{25}\right):\dfrac{4}{7}}{\left(6\dfrac{5}{9}-3\dfrac{1}{4}\right).2\dfrac{2}{17}}+\left(1,2.0,5\right):\dfrac{4}{5}\)
a) \(\dfrac{\left(3+\dfrac{1}{6}\right)-\dfrac{2}{5}}{\left(5-\dfrac{1}{6}\right)+\dfrac{7}{10}}\)
b) \(\dfrac{\left(4,08-\dfrac{2}{25}\right):\dfrac{4}{17}}{\left(6\dfrac{5}{9}-3\dfrac{1}{4}\right).2\dfrac{2}{7}}\)
c) \(\dfrac{2-\dfrac{1}{4}+\dfrac{1}{3}-\dfrac{3}{5}}{3-\dfrac{1}{5}-\dfrac{5}{3}}\)
so sanh
M=\(\left(\dfrac{1}{2^2}-1\right).\left(\dfrac{1}{3^2}-1\right).\left(\dfrac{1}{4^2}-1\right)...\left(\dfrac{1}{100^2}-1\right)\)va \(\dfrac{1}{2}\)
B=\(\dfrac{1}{20}+\dfrac{1}{21}+...+\dfrac{1}{200}va\dfrac{9}{10}\)
C=\(\dfrac{10}{17}+\dfrac{8}{15}+\dfrac{11}{16}va2\)
Tìm \(x\)
1. \(\dfrac{1}{7}=\dfrac{8}{-x}\)
2. \(\dfrac{3x}{9}=\dfrac{2}{6}\)
3. \(4\dfrac{2}{5}:\left(\dfrac{-33}{10}\right)+x=-1\dfrac{5}{6}\)
4. \(45\%.x-2\dfrac{3}{8}=-1\dfrac{31}{40}\)
5. \(\left(x-2\dfrac{1}{4}\right):\left(-\dfrac{5}{6}\right)=3\)
Bài 1: Tìm x:
a) \(\left|x+\dfrac{4}{15}\right|-\left|-3,75\right|=-\left|-2,15\right|\)
b) \(\left|\dfrac{5}{3}x\right|=\left|-\dfrac{1}{6}\right|\)
c) \(\left|\dfrac{3}{4}x-\dfrac{3}{4}\right|-\dfrac{3}{4}=\left|-\dfrac{3}{4}\right|\)
Bài 2: Tìm x,y:
a) \(\left|\dfrac{1}{2}-\dfrac{1}{3}+x\right|=\dfrac{1}{4}-\left|y\right|\)
b) \(\left|x-y\right|+\left|y+\dfrac{9}{25}\right|=0\)
Bài 3: Tìm giá trị nhỏ nhất:
a) A= \(\left|x+\dfrac{15}{19}\right|-1\)
b) B= \(\dfrac{1}{2}+\left|x-\dfrac{4}{7}\right|\)
Bài 4: Tìm giá trị lớn nhất:
a) A= 5- \(\left|\dfrac{5}{3}-x\right|\)
b) B= 9-\(\left|x-\dfrac{1}{10}\right|\)
1, so sánh A;B biết: A=\(\left(\dfrac{\left(3\cdot\dfrac{2}{15}+\dfrac{1}{5}\right):2\cdot\dfrac{1}{2}}{\left(5\cdot\dfrac{3}{7}-2\cdot\dfrac{1}{4}\right):\dfrac{443}{56}}\right);B=\dfrac{1,2:\left(1\cdot\dfrac{1}{5}.1\cdot\dfrac{1}{4}\right)}{0,32+\dfrac{2}{25}}\)
