Ôn tập toán 6
Các câu hỏi tương tự
Chứng minh các tổng sau lớn hơn 1 nhưng nhỏ hơn 2
A=\(\dfrac{6}{16}+\dfrac{15}{75}+\dfrac{35}{42}\)
1.tìm x
a) (dfrac{2}{11.13}+dfrac{2}{13.15}+...+dfrac{2}{19.21}).462-[2,04:(x+1,05)]:0,1219
b) dfrac{1}{24.25}+dfrac{1}{25.26}+...+dfrac{1}{29.30}+x:dfrac{1}{3}-4
2. thực hiện phép tính
a)dfrac{15}{28}-dfrac{186}{116}-dfrac{121}{462}+dfrac{189}{198}
b)(1+dfrac{1}{1.3}).(1+dfrac{1}{2.4}).(1+dfrac{1}{3.5})...(1+dfrac{1}{99.100})
Đọc tiếp
1.tìm x
a) (\(\dfrac{2}{11.13}+\dfrac{2}{13.15}+...+\dfrac{2}{19.21}).462-[2,04:(x+1,05)]:0,12=19\)
b) \(\dfrac{1}{24.25}+\dfrac{1}{25.26}+...+\dfrac{1}{29.30}+x:\dfrac{1}{3}=-4\)
2. thực hiện phép tính
a)\(\dfrac{15}{28}-\dfrac{186}{116}-\dfrac{121}{462}+\dfrac{189}{198}\)
b)\((1+\dfrac{1}{1.3}).(1+\dfrac{1}{2.4}).(1+\dfrac{1}{3.5})...(1+\dfrac{1}{99.100})\)
Chứng minh:
a) \(\dfrac{1}{5}+\dfrac{1}{6}+\dfrac{1}{7}+...+\dfrac{1}{17}< 2\)
b) \(\dfrac{1}{101}+\dfrac{1}{102}+...+\dfrac{1}{299}+\dfrac{1}{300}>\dfrac{2}{3}\)
Cho B = \(\dfrac{1}{4}+\dfrac{1}{5}+\dfrac{1}{6}+......+\dfrac{1}{19}\)
Hãy chứng tỏ B lớn hơn 1
Chứng minh rằng :
\(\dfrac{1}{6}< \dfrac{1}{5^2}+\dfrac{1}{6^2}+\dfrac{1}{7^2}+...+\dfrac{1}{100^2}< \dfrac{1}{4}\)
Chứng minh rằng\(\dfrac{1}{4^2} + \dfrac{1}{6^2} + \dfrac{1}{8^2} + ....... + \dfrac{1}{2n^2}< \dfrac{1}{4}\)
Cho A = \(\dfrac{1}{2}.\dfrac{3}{4}.\dfrac{5}{6}.\dfrac{7}{8}...\dfrac{79}{80}\). Chứng minh A < \(\dfrac{1}{9}\) .
\(A=1\dfrac{13}{15}.25.\dfrac{1}{100}.3+\left(\dfrac{8}{15}-\dfrac{78}{60}\right):1\dfrac{23}{24}\)
\(\dfrac{-5}{9}+1\dfrac{5}{9}\cdot\left(\dfrac{3}{4}-\dfrac{2}{5}\right):7^2\)
\(1\dfrac{13}{15}\cdot0,75-\left(\dfrac{104}{195}+25\%\right)\cdot\dfrac{24}{47}-3\dfrac{12}{13}:3\)
\(1\dfrac{13}{15}\cdot\left(0,5\right)^2\cdot3+\left(\dfrac{8}{15}+1\dfrac{19}{60}\right):1\dfrac{23}{24}\)