Ôn tập toán 7
Các câu hỏi tương tự
Cho B= \(\frac{1}{2}+\left(\frac{1}{2}\right)^2+....+\left(\frac{1}{2}\right)^{2014}+\left(\frac{1}{2}\right)^{2015}\).Chứng minh B<1
Cho A=\(\frac{1}{2}+\left(\frac{1}{2}\right)^2+\left(\frac{1}{2}\right)^3+.....+\left(\frac{1}{2}\right)^{2014}\)
Chứng minh A<1
tìm x biết
a. \(\frac{1}{4}.\left\{3-\frac{1}{2}\left[1+\frac{1}{2}\left(\sqrt{2x+1}-\frac{1}{2}\right)\right]\right\}=2\)
b. \(\sqrt{1+2+3+...+\left(x-1\right)+x+\left(x-1\right)+...+3+2+1}=2010\)
giúp mình nha mình đang cần gấp
Tính : A left(1-frac{2}{3}+frac{4}{3}right)-left(frac{4}{5}-1right)+left(frac{7}{5}+2right)B left(-3+frac{3}{4}-frac{1}{3}right):left(5+frac{2}{5}-frac{2}{3}right)C left(frac{3}{5}-frac{4}{5}right).left(frac{2}{7}-frac{3}{14}right)-left(frac{5}{9}-frac{7}{27}right).left(1-frac{3}{5}right)+left(1-frac{11}{12}right).left(1-frac{11}{12}right)
Đọc tiếp
Tính :
A = \(\left(1-\frac{2}{3}+\frac{4}{3}\right)-\left(\frac{4}{5}-1\right)+\left(\frac{7}{5}+2\right)\)
B = \(\left(-3+\frac{3}{4}-\frac{1}{3}\right):\left(5+\frac{2}{5}-\frac{2}{3}\right)\)
C = \(\left(\frac{3}{5}-\frac{4}{5}\right).\left(\frac{2}{7}-\frac{3}{14}\right)-\left(\frac{5}{9}-\frac{7}{27}\right).\left(1-\frac{3}{5}\right)+\left(1-\frac{11}{12}\right).\left(1-\frac{11}{12}\right)\)
Tính
\(\frac{\left(-5\right).\left(-0,9\right)^{2^{ }}}{\left(1\frac{1}{2}\right)^{4^{ }}.\left(-3\frac{1}{3}\right)^{3^{ }}.\left(-1\right)^{2015}}\)
tính
a) \(3^{-2}.\left[\left(\frac{2}{3}\right)^{-4}\right].\left[\left(-1\frac{1}{2}\right)^{-3}\right]\)
b) \(\left[\left(0.02\right)^{-3}\right].10^{-4}.\left(\frac{4}{5}\right)^{-2}\)
c) \(\left[2^{-2}-\frac{3}{4}^{-4}.\left(\frac{-1}{2}^2\right)\right]:\left(10^{-1}+1\right)\)
Chứng minh rằng với \(n\in N\)* thì:
a, \(1^2+2^2+3^2+...+n^2=\frac{n\left(n+1\right)\left(2n+1\right)}{6}\)
b, \(1^3+2^3+3^3+...+n^3=\left(\frac{n\left(n+1\right)}{2}\right)^2\)
c, \(n+2\left(n-1\right)+3\left(n-2\right)+...+n=\frac{n\left(n+1\right)\left(n+2\right)}{6}\)
\(\frac{5}{3}\left(3x-3\right)+\frac{1}{2}=\frac{1}{2}\left(2x-1\right)\) \(\frac{-4}{3}\left(x-\frac{1}{4}\right)=\frac{3}{2}\left(2x-1\right)\) ai giup minh voi nhanh nhanh
Tính:
a)\(\left\{\left[\left(6,2:0,31-\frac{5}{6}.0,9\right).0,2+0,15\right]:0,2\right\}:\left[\left(2+1\frac{4}{11}:0,1\right).\frac{1}{33}\right]\)
b)\(0,4\left(3\right)+0,6\left(2\right)-2\frac{1}{2}.\left[\left(\frac{1}{2}+\frac{1}{3}:0,5\left(8\right)\right)\right]:\frac{50}{53}\)
c)\(\frac{0,375-0,3+\frac{3}{11}+\frac{3}{12}}{0,625-0,5+\frac{5}{11}+\frac{5}{12}}\)