Ôn tập toán 7
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Tính B = \(1+\frac{1}{2}\left(1+2\right)+\frac{1}{3}\left(1+2+3\right)+\frac{1}{4}\left(1+2+3+4\right)+...+\frac{1}{16}\left(1+2+3+4+...+16\right)\)
30 tháng 11 2016 lúc 22:50
Tính giá trị biểu thức \(A=1+\frac{1}{2}\left(1+2\right)+\frac{1}{3}\left(1+2+3\right)+\frac{1}{4}+\left(1+2+3+4\right)+...+\frac{1}{16}+\left(1+2+3+...+16\right)\)
Giúp mk mn ơi 
\(\frac{\left[\left(e-m\right)^2-\left(e+m\right)^2\right].\left[\left(y-1\right)^2-\left(y+1\right)^2\right]}{a.16.h.n}.\frac{ê}{y^{-1}}\)
Tìm x in Za,frac{1}{2}-left(frac{1}{3}+frac{1}{4}right) x frac{1}{48}-left(frac{1}{16}-frac{1}{6}right)b, frac{3}{4}-frac{5}{6}lefrac{x}{12} 1-left(frac{2}{3}-frac{1}{3}right)c, x:left(frac{1}{2}right)^2frac{-1}{2}d,left(x^4right)^2frac{x^{12}}{x^5}left(xne0right)e,frac{3^2.3^8}{27^3}3^xf,2^{x-1}left(16right)^5
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Tìm x \(\in\) Z
a,\(\frac{1}{2}-\left(\frac{1}{3}+\frac{1}{4}\right)< x< \frac{1}{48}-\left(\frac{1}{16}-\frac{1}{6}\right)\)
b, \(\frac{3}{4}-\frac{5}{6}\le\frac{x}{12}< 1-\left(\frac{2}{3}-\frac{1}{3}\right)\)
c, \(x:\left(\frac{1}{2}\right)^2=\frac{-1}{2}\)
d,\(\left(x^4\right)^2=\frac{x^{12}}{x^5}\left(x\ne0\right)\)
e,\(\frac{3^2.3^8}{27^3}=3^x\)
f,\(2^{x-1}=\left(16\right)^5\)
Thực hiện phép tínha)16frac{2}{7}:left(frac{-3}{5}right)+28frac{2}{7}:frac{3}{5}b)left(2^2:frac{4}{3}-frac{1}{2}right).frac{6}{5}-17c)left(frac{1}{3}right)^{50}.left(-9right)^{25}-frac{2}{3}:4d)frac{3}{5}:left(frac{-1}{15}-frac{1}{6}right)+frac{3}{5}:left(frac{-1}{3}-1frac{1}{15}right)e)left(-6,5right).5,7+5,7.left(-3,5right)
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Thực hiện phép tính
a)\(16\frac{2}{7}:\left(\frac{-3}{5}\right)+28\frac{2}{7}:\frac{3}{5}\)
b)\(\left(2^2:\frac{4}{3}-\frac{1}{2}\right).\frac{6}{5}-17\)
c)\(\left(\frac{1}{3}\right)^{50}.\left(-9\right)^{25}-\frac{2}{3}:4\)
d)\(\frac{3}{5}:\left(\frac{-1}{15}-\frac{1}{6}\right)+\frac{3}{5}:\left(\frac{-1}{3}-1\frac{1}{15}\right)\)
e)\(\left(-6,5\right).5,7+5,7.\left(-3,5\right)\)
rút gona,frac{2.5^{22}-9.5^{21}}{25^{10}}b,frac{5left(3.7^{15}-19.7^{14}right)}{7^{16}+3.7^{15}}c,frac{left(left(-2right)^2right)^3.left(-4right)^2}{left(-2right)^3.left(-2right)^2} d,frac{4^6.9^5+6^9.120}{8^4.3^{12}-6^{11}}e,2^3+3.left(frac{1}{8}right)^0-left(frac{1}{2^2}right).4+left[left(-2right)^2:frac{1}{2}right].8f,frac{left(frac{2}{5}right)^7.5^5+left(frac{9}{4}right)^3:left(frac{3}{16}right)^3}{2^7.5^2+512}
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rút gon
a,\(\frac{2.5^{22}-9.5^{21}}{25^{10}}\)
b,\(\frac{5\left(3.7^{15}-19.7^{14}\right)}{7^{16}+3.7^{15}}\)
c,\(\frac{\left(\left(-2\right)^2\right)^3.\left(-4\right)^2}{\left(-2\right)^3.\left(-2\right)^2}\)
d,\(\frac{4^6.9^5+6^9.120}{8^4.3^{12}-6^{11}}\)
e,\(2^3+3.\left(\frac{1}{8}\right)^0-\left(\frac{1}{2^2}\right).4+\left[\left(-2\right)^2:\frac{1}{2}\right].8\)
f,\(\frac{\left(\frac{2}{5}\right)^7.5^5+\left(\frac{9}{4}\right)^3:\left(\frac{3}{16}\right)^3}{2^7.5^2+512}\)
Tính giá trị biểu thức:
A = \(\frac{15}{34}+\frac{7}{21}+\frac{9}{34}-1\frac{15}{17}+\frac{2}{3}\) B = \(16\frac{2}{7}:\left(-\frac{3}{5}\right)-28\frac{2}{7}:\left(-\frac{3}{5}\right)\)
C = 25.\(\left(-\frac{1}{3}\right)^3+\frac{1}{5}-2.\left(-\frac{1}{2}\right)^2-\frac{1}{2}\)
Rút gọn biểu thức A = \(\left(2-1\frac{1}{4}\right)\left(2-1\frac{1}{9}\right)\left(2-1\frac{1}{16}\right)...\left(2-1\frac{1}{400}\right)\)
1) tìm x biết
a) \(\left(\frac{2}{3}\right)^x=\left(\frac{4}{9}\right)^{50}\)
b) \(\left(\frac{2}{3}-x\right)^2=\frac{1}{36}\)
c)\(\left(x-\frac{1}{2}\right)^{50}-\left(\frac{1}{3}\right)^{20}\times\left(-\frac{1}{9}\right)^{15}\)
2) chứng tỏ
\(\left(74^{m+1}+74^m\right)⋮25\)