BT3: Tính nhanh:
1) \(\dfrac{5}{18}+\dfrac{4}{7}+\dfrac{13}{18}+\dfrac{3}{7}\)
2) \(\dfrac{4}{9}.\dfrac{5}{19}.\dfrac{9}{4}\)
BT3: Tìm x, biết
18) \(\dfrac{x+24}{1996}+\dfrac{x+25}{1995}+\dfrac{x+26}{1994}+\dfrac{x+27}{1993}+\dfrac{x+2036}{4}=0\)
BT3: Tìm x, biết
10) \(\left(\dfrac{2x}{5}-1\right):\left(-5\right)=\dfrac{1}{4}\)
12) \(\left(3\dfrac{1}{4}:x\right).\left(-1\dfrac{1}{4}\right)=-\dfrac{5}{3}-\dfrac{5}{6}\)
BT3: Tìm x, biết
13) \(\left(-1\dfrac{1}{5}+x\right):\left(-3\dfrac{3}{5}\right)=\dfrac{-7}{4}+\dfrac{1}{4}:\dfrac{1}{8}\)
14) \(\dfrac{11}{13}-\left(\dfrac{5}{42}-x\right)=-\left(\dfrac{15}{28}-\dfrac{11}{13}\right)\)
BT3: Tìm x, biết
15) \(2\text{|}\dfrac{1}{2}x-\dfrac{1}{3}\text{|}-\dfrac{3}{2}=\dfrac{1}{4}\)
16) \(\dfrac{3}{4}-2.\text{|}2x-\dfrac{2}{3}\text{|}=2\)
(Lưu ý: Dấu '' | '' là dấu giá trị tuyệt đối)
BT3: Tìm x, biết
19) \(\left(\dfrac{1}{1.2.3}+\dfrac{1}{2.3.4}+...+\dfrac{1}{8.9.10}\right).x=\dfrac{23}{45}\)
BT3: Tìm x, biết
21) \(\dfrac{1}{5.8}+\dfrac{1}{8.11}+\dfrac{1}{11.14}+...+\dfrac{1}{x.\left(x+3\right)}=\dfrac{101}{1540}\)
BT3: Tìm x, biết
20) \(\dfrac{1}{3}+\dfrac{1}{6}+\dfrac{1}{10}+...+\dfrac{1}{x.\left(x+1\right):2}=\dfrac{1998}{2000}\)
BT3: Tính nhanh:
3) 3,67.58,35 +58,35 . 6,33
