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\(\frac{4}{3x7}\)+ \(\frac{5}{7x12}\)+ \(\frac{1}{12x13}\)+ \(\frac{7}{13x20}\)+ \(\frac{3}{20x23}\)
= \(\frac{4}{3}+5\)+\(1+7+\frac{3}{13}\)
=\(4+5+1+7+\frac{1}{13}\)
=\(17+\frac{1}{13}\)
=\(\frac{17}{1}+\frac{1}{13}=\frac{221+1}{13}=\frac{222}{13}\)
\(x-\left(\frac{20}{11.13}+\frac{20}{13.15}+\frac{20}{15.17}+...+\frac{20}{53.55}\right)=\frac{3}{11}\)
\(x-10\left(\frac{2}{11.13}+\frac{2}{13.15}+\frac{2}{15.17}+...+\frac{2}{53.55}\right)=\frac{3}{11}\)
\(x-10\left(\frac{1}{11}-\frac{1}{13}+\frac{1}{13}-\frac{1}{15}+\frac{1}{15}-\frac{1}{17}+...+\frac{1}{53}-\frac{1}{55}\right)=\frac{3}{11}\)
\(x-10\left(\frac{1}{11}-\frac{1}{55}\right)=\frac{3}{11}\)
\(x-10.\frac{4}{55}=\frac{3}{11}\)
\(x-\frac{40}{55}=\frac{3}{11}\)
\(x=\frac{3}{11}+\frac{40}{55}\)
\(x=\frac{55}{55}=1\)
nha.
=\(2-\frac{2}{3}+\frac{2}{3}-\frac{2}{5}+\frac{2}{5}-\frac{2}{7}+....+\frac{2}{11}-\frac{2}{13}\)
=2-\(\frac{2}{13}\)=\(\frac{24}{13}\)
\(\frac{5^2\times6^{11}\times16^2+6^2\times12^6\times15^2}{2\times6^{12}\times10^4-81^2\times960^3}\)
\(=\frac{5^2\times\left(2\times3\right)^{11}\times\left(2^4\right)^2+\left(2\times3\right)^2\times\left(2^2\times3\right)^6\times\left(3\times5\right)^2}{2\times\left(2\times3\right)^{12}\times\left(2\times5\right)^4-\left(3^4\right)^2\times\left(2^6\times3\times5\right)^3}\)
\(=\frac{5^2\times2^{19}\times3^{11}+2^{14}\times3^{10}\times5^3}{2^{17}\times5^4\times3^{12}-3^{11}\times2^{18}\times5^3}\)
\(=\frac{5^2\times3^{10}\times2^{14}\times\left(2^5\times3+5\right)}{2^{17}\times5^3\times3^{11}\times\left(5\times3-2\right)}\)
\(=\frac{2^5\times3+5}{2^3\times5\times3\times12}\)
\(=\frac{32\times3+5}{8\times15\times12}=\frac{96+5}{120\times12}=\frac{101}{1440}\)
1/5x8 + 1/8x11 + 1/11x14 + ... + 1/xx(x+3) = 101/1540
1/3 x (3/5x8 + 3/8x11 + 3/11x14 + ... + 3/xx(x+3) = 101/1540
1/3 x (1/5 - 1/8 + 1/8 - 1/11 + 1/11 - 1/14 + ... + 1/x - 1/x+3) = 101/1540
1/3 x (1/5 - 1/x+3) = 101/1540
1/5 - 1/x+3 = 101/1540 : 1/3
1/5 - 1/x+3 = 303/1540
1/x+3 = 1/5 - 303/1540
1/x+3 = 1/308
=> x+3=308
=> x=308-3=305
vậy x=305
1/5x8 + 1/8x11 + 1/11x14 + ... + 1/xx(x+3) = 101/1540
1/3 x (3/5x8 + 3/8x11 + 3/11x14 + ... + 3/xx(x+3) = 101/1540
1/3 x (1/5 - 1/8 + 1/8 - 1/11 + 1/11 - 1/14 + ... + 1/x - 1/x+3) = 101/1540
1/3 x (1/5 - 1/x+3) = 101/1540
1/5 - 1/x+3 = 101/1540 : 1/3
1/5 - 1/x+3 = 303/1540
1/x+3 = 1/5 - 303/1540
1/x+3 = 1/308
=> x+3=308
=> x=308-3=305
vậy x=305
11 x 12 x 13 x14 = 24024.
11x12x13x14=24024
ai k cho mk thì mk k lại cho kích mau ko hết nha