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15 tháng 12 2021
\(=\left(\dfrac{1}{2}+\dfrac{1}{2}\right)-\left(\dfrac{5}{41}+\dfrac{36}{41}\right)=1-1=0\)
6 tháng 11 2016
Bài 1:
a)\(\frac{2}{3}.\frac{5}{2}-\frac{3}{4}.\frac{2}{3}=\frac{5}{3}-\frac{1}{2}=\frac{7}{6}\)
b)\(2.\left(\frac{-3}{2}\right)^2-\frac{7}{2}=\frac{2.9}{4}-\frac{7}{2}=\frac{9-7}{2}=\frac{2}{2}=1\)
c)\(-\frac{3}{4}.\frac{68}{13}-0,75.\frac{36}{13}=\frac{-3.4.17}{4.13}-\frac{3.9.4}{4.13}=\frac{-51-27}{13}=\frac{-78}{13}=-6\)
Bài 2:
a)|x-1,4|=1,6
\(\Rightarrow\left[\begin{array}{nghiempt}x-1,4=1,6\\x-1,4=-1,6\end{array}\right.\)
\(\Rightarrow\left[\begin{array}{nghiempt}x=3\\x=-0,2\end{array}\right.\)
b) \(\frac{3}{4}-x=\frac{4}{5}\)
\(x=\frac{3}{4}-\frac{4}{5}=-\frac{1}{20}\)
c)(1-2x)3=-8
(1-2x)3=(-2)3
1-2x=-2
2x=3
x=\(\frac{3}{2}\)
Bài 3:
\(\frac{x}{2}=\frac{y}{5}=\frac{z}{7}=k\)
\(\Rightarrow\begin{cases}x=2k\\y=5k\\z=7k\end{cases}\)
A=\(\frac{2k-5k+7k}{2k+2.5k-7k}=\frac{4k}{5k}=\frac{4}{5}\)
=> x=4/5 . 2= 8/5
y=4/5 . 5=4
z=4/5.7=28/5
30 tháng 12 2021
a) (-124) + 24 = -100
b) 37. 78 + 37. 22
= 37 . ( 78 + 22 )
= 37 . 100
= 3700
5 tháng 7 2023
e: =5/7(5/11+2/11-14/11)
=5/7(-7/11)=-5/11
f: =-5/4(2/11+9/11)+1+3/4
=-5/4+7/4
=2/4=1/2
g: =-5/7(3/13+10/13)+1+5/7
=-5/7+1+5/7
=1
h: =7/4(29/5-9/5)+41/13
=-7+41/13=-50/13
6 tháng 1 2022
d: A={-4;-3;-2;-1;0;1}
Tổng là: (-4)+(-3)+(-2)+(-1+1)+0=-9
5 tháng 3 2022
a: \(\left(\dfrac{x+2}{x+1}-\dfrac{2x}{x-1}\right)\cdot\dfrac{3x+3}{x}+\dfrac{4x^2+x+7}{x^2-x}\)
\(=\dfrac{x^2+x-2-2x^2-2x}{\left(x+1\right)\left(x-1\right)}\cdot\dfrac{3\left(x+1\right)}{x}+\dfrac{4x^2+x+7}{x\left(x-1\right)}\)
\(=\dfrac{-x^2-x-2}{x-1}\cdot\dfrac{3}{x}+\dfrac{4x^2+x+7}{x\left(x-1\right)}\)
\(=\dfrac{-3x^2-3x-6+4x^2+x+7}{x\left(x-1\right)}=\dfrac{x^2-2x+1}{x\left(x-1\right)}=\dfrac{x-1}{x}\)
CN
1
H9
HT.Phong (9A5)
CTVHS
12 tháng 8 2023
\(63,95\times83,567+6,395\times164,33\)
\(=63,95\times83,567+6,395\times16,433\times10\)
\(=63,95\times83,567+63,95\times16,433\)
\(=63,95\times\left(83,567+16,433\right)\)
\(=63,95\times100\)
\(=6395\)
DP
3
1: \(\dfrac{-5}{12}\cdot\dfrac{2}{11}+\dfrac{-5}{12}\cdot\dfrac{9}{11}+\dfrac{5}{12}\)
\(=-\dfrac{5}{12}\left(\dfrac{2}{11}+\dfrac{9}{11}\right)+\dfrac{5}{12}\)
\(=-\dfrac{5}{12}+\dfrac{5}{12}=0\)
2: \(\dfrac{-3}{5}:\dfrac{7}{5}+\dfrac{3}{5}:\dfrac{7}{5}+2\dfrac{3}{5}\)
\(=\left(-\dfrac{3}{5}+\dfrac{3}{5}\right):\dfrac{7}{5}+\dfrac{13}{5}\)
\(=0\cdot\dfrac{5}{7}+\dfrac{13}{5}=\dfrac{13}{5}\)
3: \(\dfrac{-3}{7}\cdot\dfrac{5}{9}+\dfrac{4}{9}\cdot\dfrac{-3}{7}+\left(-2022\right)^0\)
\(=\dfrac{-3}{7}\left(\dfrac{5}{9}+\dfrac{4}{9}\right)+1\)
\(=-\dfrac{3}{7}+1=\dfrac{4}{7}\)
4: \(0,75-\left(2\dfrac{1}{3}+0,75\right)+3^2\cdot\dfrac{-1}{9}\)
\(=0,75-\dfrac{7}{3}-0,75+9\cdot\dfrac{-1}{9}\)
\(=-\dfrac{7}{3}-1=-\dfrac{10}{3}\)
5: \(2\dfrac{6}{7}\cdot\left[\left(-\dfrac{7}{5}-\dfrac{3}{2}:\dfrac{-5}{-4}\right)+\left(\dfrac{3}{2}\right)^2\right]\)
\(=\dfrac{20}{7}\cdot\left[-\dfrac{7}{5}-\dfrac{3}{2}\cdot\dfrac{4}{5}+\dfrac{9}{4}\right]\)
\(=\dfrac{20}{7}\left(-\dfrac{7}{5}-\dfrac{3}{10}+\dfrac{9}{4}\right)\)
\(=\dfrac{20}{7}\cdot\dfrac{-28-6+45}{20}\)
\(=\dfrac{45-34}{7}=\dfrac{11}{7}\)
6: \(\dfrac{2}{7}+\dfrac{5}{7}\left(\dfrac{3}{5}-0,25\right)\cdot\left(-2\right)^2+35\%\)
\(=\dfrac{2}{7}+\dfrac{5}{7}\left(\dfrac{3}{5}-\dfrac{1}{4}\right)\cdot4+\dfrac{7}{20}\)
\(=\dfrac{2}{7}+\dfrac{7}{20}+\dfrac{20}{7}\cdot\dfrac{7}{20}\)
\(=\dfrac{89}{140}+1=\dfrac{239}{140}\)
7: \(1\dfrac{13}{15}\cdot0,75-\left(\dfrac{11}{20}+25\%\right):1\dfrac{2}{5}\)
\(=\dfrac{28}{15}\cdot\dfrac{3}{4}-\left(\dfrac{11}{20}+\dfrac{5}{20}\right):\dfrac{7}{5}\)
\(=\dfrac{21}{15}-\dfrac{16}{20}\cdot\dfrac{5}{7}\)
\(=\dfrac{7}{5}-\dfrac{4}{7}=\dfrac{49-20}{35}=\dfrac{29}{35}\)
8: \(\left(-2,4+\dfrac{1}{3}\right):3\dfrac{1}{10}+75\%:1\dfrac{1}{2}\)
\(=\left(-\dfrac{12}{5}+\dfrac{1}{3}\right):\dfrac{31}{10}+\dfrac{3}{4}:\dfrac{3}{2}\)
\(=\dfrac{-31}{15}\cdot\dfrac{10}{31}+\dfrac{1}{2}\)
\(=-\dfrac{2}{3}+\dfrac{1}{2}=\dfrac{-4+3}{6}=\dfrac{-1}{6}\)