cái này cồng kềnh nhưng ko khó - >ngại. Bn tính 2/11*13+.... trước bằng cách rút gọn sau đó nhân ra -> dễ
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\(\left(\dfrac{2}{11.13}+\dfrac{2}{13.15}+...+\dfrac{2}{19.21}\right).462-\left[0,04:\left(x+1,05\right)\right]:0,12=19\) hãy tìm x
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)\((1+\dfrac{1}{1.3}).(1+\dfrac{1}{2.4}).(1+\dfrac{1}{3.5})...(1+\dfrac{1}{99.100})\)
Tìm x biết:
a) \(\dfrac{x+5}{3}\)=\(\dfrac{x-6}{7}\)
b) x - \(\dfrac{20}{11.13}\)-\(\dfrac{20}{13.15}\)-\(\dfrac{20}{15.17}\)-...-\(\dfrac{20}{53.55}\)=\(\dfrac{3}{11}\)
\(\dfrac{1}{3}\)+\(\dfrac{1}{6}\)+\(\dfrac{1}{10}\)+...+\(\dfrac{2}{n\left(n+1\right)}\)=\(\dfrac{2015}{2016}\)
tìm x biết
a) \(\dfrac{2x-3}{3}+-\dfrac{3}{2}=\dfrac{5-2x}{6}-\dfrac{1}{2}\)
b) \(\left(3x-\dfrac{1}{2}\right).\left(3-\dfrac{1}{2}x\right).\left(1+\dfrac{3}{4}:x\right)=0\)
c) \(\left(3-\dfrac{9}{10}-|x+2|\right):\left(\dfrac{19}{20}-1-\dfrac{2}{3}\right)+\dfrac{4}{5}=1\)
tìm x biết
left(3dfrac{1}{2}+2xright).2dfrac{2}{3}5dfrac{1}{3}
dfrac{3}{4}-2.left|2x-dfrac{2}{3}right|2
left(0.6-dfrac{1}{2}right).dfrac{3}{4}-left(-1right)dfrac{1}{3}
left(3x-1right).left(-dfrac{1}{2}x+5right)0
dfrac{1}{4}+dfrac{1}{3}:left(2x-1right)-5
left(2x+dfrac{3}{5}right)^2-dfrac{9}{25}0
-5.left(x+dfrac{1}{5}right)-dfrac{1}{2}.left(x-dfrac{2}{3}right)dfrac{3}{2}x-dfrac{5}{6}
Đọc tiếp
tìm x biết
\(\left(3\dfrac{1}{2}+2x\right).2\dfrac{2}{3}=5\dfrac{1}{3}\)
\(\dfrac{3}{4}-2.\left|2x-\dfrac{2}{3}\right|=2\)
\(\left(0.6-\dfrac{1}{2}\right).\dfrac{3}{4}-\left(-1\right)=\dfrac{1}{3}\)
\(\left(3x-1\right).\left(-\dfrac{1}{2}x+5\right)=0\)
\(\dfrac{1}{4}+\dfrac{1}{3}:\left(2x-1\right)=-5\)
\(\left(2x+\dfrac{3}{5}\right)^2-\dfrac{9}{25}=0\)
\(-5.\left(x+\dfrac{1}{5}\right)-\dfrac{1}{2}.\left(x-\dfrac{2}{3}\right)=\dfrac{3}{2}x-\dfrac{5}{6}\)
\(a,-\dfrac{2}{3}.\left(x-\dfrac{1}{4}\right)=\dfrac{1}{3}.\left(2x-1\right)\)
\(b,\dfrac{1}{5}.2^x+\dfrac{1}{3}.2^{x+11}=\dfrac{1}{5}.2^7+\dfrac{1}{3}.2^8\)
\(c,\dfrac{x-19}{345}+\dfrac{x-20}{346}=\dfrac{x-1}{347}+\dfrac{x-22}{348}\)
tìm x:
a)\(\left(x+\dfrac{1}{2}\right).\left(\dfrac{2}{3}-2x\right)=0\)
b) \(\left(x.6\dfrac{2}{7}+\dfrac{3}{7}\right).2\dfrac{1}{5}-\dfrac{3}{7}=-2\)
c) \(x.3\dfrac{1}{4}+\left(\dfrac{-7}{6}\right).x-1\dfrac{2}{3}=\dfrac{5}{12}\)
d) \(5\dfrac{8}{17}:x+\left(-\dfrac{4}{17}\right):x+3\dfrac{1}{7}:17\dfrac{1}{3}=\dfrac{4}{11}\)
BT1: Tìm x, biết
2)\(2+\dfrac{5}{7}+\left(\dfrac{\dfrac{3}{19}+\dfrac{3}{23}-\dfrac{3}{28}}{\dfrac{5}{19}+\dfrac{5}{23}-\dfrac{5}{28}}\right).x=\dfrac{20}{7}\)
left(2x-3right)left(6-2xright)0
dfrac{1}{3}x+dfrac{2}{5}left(x-1right)0
left(3x-1right)left(-dfrac{1}{2}x+5right)0
dfrac{x}{5}dfrac{2}{3}
dfrac{x}{3}-dfrac{1}{2}dfrac{1}{5}
dfrac{x}{5}-dfrac{1}{2}dfrac{6}{10}
dfrac{x+3}{15}dfrac{1}{3}
dfrac{x-12}{4}dfrac{1}{2}
Đọc tiếp
\(\left(2x-3\right)\left(6-2x\right)=0\)
\(\dfrac{1}{3}x+\dfrac{2}{5}\left(x-1\right)=0\)
\(\left(3x-1\right)\left(-\dfrac{1}{2}x+5\right)=0\)
\(\dfrac{x}{5}=\dfrac{2}{3}\)
\(\dfrac{x}{3}-\dfrac{1}{2}=\dfrac{1}{5}\)
\(\dfrac{x}{5}-\dfrac{1}{2}=\dfrac{6}{10}\)
\(\dfrac{x+3}{15}=\dfrac{1}{3}\)
\(\dfrac{x-12}{4}=\dfrac{1}{2}\)