Các câu hỏi tương tự
Cho A=\(\frac{1}{5^2}+\frac{1}{6^2}+\frac{1}{7^2}+...+\frac{1}{100^2}\)
CMR \(\frac{1}{6}< A< \frac{1}{4}\)
\(A=\left(2+4+6+...+100\right)\left(\frac{3}{5}:0,7+3\left(\frac{-2}{7}\right)\right):\left(\frac{1}{2}+\frac{1}{4}+\frac{1}{6}+...+\frac{1}{100}\right)\)
tính nhanh : Afrac{15^3+5times15^2-5^3}{18^3+6times18^2-6^3}Bfrac{1}{3}+frac{1}{3^2}+frac{1}{3^3}+....+frac{1}{3^{2015}}C1+frac{1}{2}left(1+2right)+frac{1}{3}left(1+2+3right)+...+frac{1}{16}left(1+2+...+16right) Dfrac{0,4-frac{2}{9}+frac{2}{11}}{1,4-frac{7}{9}+frac{7}{11}}-frac{frac{1}{3}-0,25+frac{1}{5}}{1frac{1}{6}-0,875+0,7} Fleft(100-1^2right)left(100-2^2right)....left(100-25^2right)
Đọc tiếp
tính nhanh :
\(A=\frac{15^3+5\times15^2-5^3}{18^3+6\times18^2-6^3}\)
\(B=\frac{1}{3}+\frac{1}{3^2}+\frac{1}{3^3}+....+\frac{1}{3^{2015}}\)
\(C=1+\frac{1}{2}\left(1+2\right)+\frac{1}{3}\left(1+2+3\right)+...+\frac{1}{16}\left(1+2+...+16\right)\) \(D=\frac{0,4-\frac{2}{9}+\frac{2}{11}}{1,4-\frac{7}{9}+\frac{7}{11}}-\frac{\frac{1}{3}-0,25+\frac{1}{5}}{1\frac{1}{6}-0,875+0,7}\)
\(F=\left(100-1^2\right)\left(100-2^2\right)....\left(100-25^2\right)\)
1) Tinh gia tri cua bieu thuc:
A=\(\frac{\left(1+2+...+100\right)\left(\frac{1}{2}-\frac{1}{3}-\frac{1}{4}-\frac{1}{5}\right)\left(2,4.42-21.4,8\right)}{1+\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+...+\frac{1}{100}}\)
B=\(\frac{4^6.9^5+6^9.120}{-8^4.3^{12}+6^{11}}\)
\(\frac{1}{5^2}+\frac{1}{6^2}+\frac{1}{7^2}+...+\frac{1}{100^2}\)
Chứng minh \(\frac{1}{6}< C< \frac{1}{4}\)
CMR :
a) \(\frac{1}{3}+\frac{1}{31}+\frac{1}{35}+\frac{1}{37}+\frac{1}{47}+\frac{1}{53}+\frac{1}{61}< \frac{1}{2}\)
b) \(\frac{1}{6}< \frac{1}{5^2}+\frac{1}{6^2}+....+\frac{1}{100^2}< \frac{1}{4}\)
Rút gọn A=\(\frac{\left(1+2+3+......+99+100\right).\left(\frac{1}{4}+\frac{1}{6}-\frac{1}{2}\right).\left(63.1,2-21.3,6+1\right)}{1-2+3-4+5-6+.........+99-100}\)=...
a. CMR \(\frac{1}{6}<\frac{1}{5^2}+\frac{1}{6^2}+\frac{1}{7^2}+...+\frac{1}{100^2}<\frac{1}{4}\)
b.Tìm số nguyên a để : \(\frac{2a+9}{a+3}+\frac{5a+17}{a+3}-\frac{3a}{a+3}\) là số nguyên
Bài 1 thực hiện phép tính a)frac{45}{19}-left(frac{1}{2}+left(frac{1}{3}+left(frac{1}{4}right)^{-1}right)^{-1}right)^{-1}.b) frac{5.4^{15}.9^9-4.3^{20}.8^9}{5.2^{10}.6^{19}-7.2^{29}.27^6}.Bài 2. tìm x, biết: a) 2(x-1) - 3(2x+2) - 4(2x+3) 16 b) 3frac{1}{2}:left|2x-1right|frac{21}{22} c) |x2+|x-1|| x2+2Bài 3. Chứng minh rằng số có dạng abcabc luôn chia hết cho 11Bài 4.tính:a) A left(frac{0,4-frac{2}{9}+frac{2}{11}}{1,4-frac{7}{9}+frac{7}{11}}-frac{frac{1}{3}-0,25+frac{1}{5}}{1frac{1}{6}-0,875...
Đọc tiếp
Bài 1 thực hiện phép tính
a)\(\frac{45}{19}-\left(\frac{1}{2}+\left(\frac{1}{3}+\left(\frac{1}{4}\right)^{-1}\right)^{-1}\right)^{-1}.\)
b) \(\frac{5.4^{15}.9^9-4.3^{20}.8^9}{5.2^{10}.6^{19}-7.2^{29}.27^6}.\)
Bài 2. tìm x, biết:
a) 2(x-1) - 3(2x+2) - 4(2x+3) =16
b) \(3\frac{1}{2}:\left|2x-1\right|=\frac{21}{22}\)
c) |x2+|x-1|| = x2+2
Bài 3. Chứng minh rằng số có dạng abcabc luôn chia hết cho 11
Bài 4.tính:
a) A = \(\left(\frac{0,4-\frac{2}{9}+\frac{2}{11}}{1,4-\frac{7}{9}+\frac{7}{11}}-\frac{\frac{1}{3}-0,25+\frac{1}{5}}{1\frac{1}{6}-0,875+0,7}\right):\frac{2012}{2013}\)
b) B =\(4.\left(-\frac{1}{2}\right)^2-2.\left(-\frac{1}{2}\right)^2+3.\left(-\frac{1}{2}\right)+1\)
c) C =\(\frac{1}{2}:\left(-1\frac{1}{2}\right):1\frac{1}{3}:\left(-1\frac{1}{4}\right):1\frac{1}{5}:\left(-1\frac{1}{6}\right):...:\left(-1\frac{1}{100}\right)\)
d) D =\(\frac{4^6.9^5+6^9.120}{-8^4.3^{12}+6^{11}}\)