3/4 + ( 1/2 - 5 ) . 2/9
= 3/4 + -9/2 . 2/9
= 3/4 + -1 = -1/4
3/4+(1/2-10/2).2/9
=3/4+-9/2.2/9
=3/4+(-1)
=-1/4
câu 1: (x+\(\dfrac{1}{2}\)).(\(\dfrac{2}{3}\)-2x)=0
câu 2: (3x-10)(-\(\dfrac{1}{2}\)x+5)=0
câu 3: \(\dfrac{1}{3}\)x+\(\dfrac{53}{4}\)=\(\dfrac{65}{4}\)
câu 4: \(\dfrac{2}{3}\)x-\(\dfrac{4}{9}\)=\(\dfrac{2}{9}\)
câu 5: \(\dfrac{1}{1.2}\)+\(\dfrac{1}{2.3}\)+...+\(\dfrac{1}{x\left(x+1\right)}\)=\(\dfrac{2010}{2011}\)
a, A = \(\dfrac{-7}{8}.\dfrac{5}{9}-\dfrac{4}{9}.\dfrac{7}{8}+5\dfrac{7}{8}\)
b, B = 0,25.\(1\dfrac{3}{5}.\left(\dfrac{5}{4}\right)^2:\left(\dfrac{-4}{7}\right)\)
Thực hiện phép tính ( tính nhanh nếu có thể )
a)\(\dfrac{4}{11}.\dfrac{2}{5}+\dfrac{4}{5}.\dfrac{9}{11}+\dfrac{5}{6}\)
b)\(2\dfrac{1}{2}.60\%-\left(\dfrac{3}{7}+0,15\right):\dfrac{3}{10}\)
c)\(15\dfrac{3}{13}-\left(3\dfrac{4}{7}+8\dfrac{3}{13}\right)\)
d)\(\dfrac{-7}{9}.\dfrac{4}{11}+\dfrac{-7}{9}.\dfrac{7}{11}+5\dfrac{7}{9}\)
e)\(50\%.1\dfrac{1}{3}.10.\dfrac{7}{35}.0,75\)
\(4\dfrac{1}{4}+\dfrac{2}{3}:x=5\dfrac{4}{9}\)
Tìm x:
a) (2x - 3)(6 - 2x) = 0
b) \(5\dfrac{4}{7}:x=13\)
c) 2x - \(\dfrac{3}{7}\) = \(6\dfrac{2}{7}\)
d) \(\dfrac{x}{5}\) + \(\dfrac{1}{2}\) = \(\dfrac{6}{10}\)
e) \(\dfrac{x+3}{15}=\dfrac{1}{3}\)
f) \(\dfrac{x-12}{4}=\dfrac{1}{2}\)
g) \(2\dfrac{1}{4}\).\(\left(x-7\dfrac{1}{3}\right)=1,5\)
h) \(\left(4,5-2x\right).1\dfrac{4}{7}=\dfrac{11}{14}\)
i) \(\dfrac{2}{3}\left(x-25\%\right)=\dfrac{1}{6}\)
k) \(\dfrac{3}{2}x-1\dfrac{1}{2}=x-\dfrac{3}{4}\)
\(\dfrac{-5}{7}\)+\(\dfrac{3}{4}\)+\(\dfrac{-2}{10}\)+\(\dfrac{-2}{7}\)+\(\dfrac{1}{4}\)
Tìm x :
a) 0,75x - x + \(1\dfrac{1}{4}\)x = 20%
b) \(\dfrac{1}{3}\)- x =\(\dfrac{-1}{2}\)+\(\dfrac{2}{3}\)
c)\(\dfrac{x-1}{45}\)=\(\dfrac{-3}{5}\).\(\dfrac{2}{6}\)
d) \(\left(\dfrac{2x}{5}-1\right)\):(-5)=\(\dfrac{1}{7}\)
Mình k vội nên có gì tính kĩ giùm mình nkaa <3 . Cơ mak giảng từng bước tính cho mình luôn cũm đựt ấy :) . Thankiuu nkiềuu nkaaa
Chứng minh rằng:\(\dfrac{1}{3^2}\)+ \(\dfrac{1}{4^2}\)+\(\dfrac{1}{5^2}\) + \(\dfrac{1}{6^2}\)+...+\(\dfrac{1}{100^2}\) <\(\dfrac{1}{2}\)
Mình cần gấp!
quy đồng
1. \(\dfrac{-5}{14},\dfrac{3}{20},\dfrac{9}{70}\)
2.\(\dfrac{10}{42},\dfrac{-3}{28},\dfrac{-55}{132}\)
3.\(\dfrac{7}{10},\dfrac{1}{33}\)
