2./1/2-x/-1/4=7/4
"/..../" là trị tuyệt đối nha
1/2 , 1/4 , 7/4 là phân số
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a) |-45| + |-15| : 3 + |10|.5
= 45 + 15 : 3 + 10.5
= 45 + 5 + 50 = 100
b) \(\frac{3^2}{1.4}+\frac{3^2}{4.7}+\frac{3^2}{7.10}+\frac{3^2}{10.13}+\frac{3^2}{13.16}\)
\(=3\left(\frac{3}{1.4}+\frac{3}{4.7}+\frac{3}{7.10}+\frac{3}{10.13}+\frac{3}{13.16}\right)\)
\(=3\left(1-\frac{1}{4}+\frac{1}{4}-\frac{1}{7}+\frac{1}{7}-\frac{1}{10}+\frac{1}{10}-\frac{1}{13}+\frac{1}{13}-\frac{1}{16}\right)\)
\(=3\left(1-\frac{1}{16}\right)=3.\frac{15}{16}=\frac{45}{16}\)
a) \(\frac{3}{2}-\left(x-\frac{7}{3}\right)=\left|-\frac{3}{4}-\frac{9}{8}\right|\)
=> \(\frac{3}{2}-x+\frac{7}{3}=\left|-\frac{15}{8}\right|\)
=> \(\frac{3}{2}-x+\frac{7}{3}=\frac{15}{8}\)
=> \(\frac{3}{2}-x=-\frac{11}{24}\)
=> \(x=\frac{47}{24}\)
b) \(\frac{5}{2}-\left(\frac{3}{2}-\frac{7}{3}+x\right)=\frac{8}{15}-\left(\frac{1}{4}-\frac{7}{10}\right)\)
=> \(\frac{5}{2}-\frac{3}{2}+\frac{7}{3}-x=\frac{8}{15}-\left(-\frac{9}{20}\right)\)
=> \(\frac{10}{3}-x=\frac{59}{60}\)
=> \(x=\frac{10}{3}-\frac{59}{60}=\frac{47}{20}\)
c) \(2\left(\frac{3}{4}-5x\right)=\frac{4}{5}-3x\)
=> \(\frac{3}{2}-10x-\frac{4}{5}+3x=0\)
=> \(\left(\frac{3}{2}-\frac{4}{5}\right)+\left(-10x+3x\right)=0\)
=> \(\frac{7}{10}-7x=0\)
=> \(7x=\frac{7}{10}\)
=> x = 1/10
\(a,\left|x+\dfrac{4}{5}\right|-\dfrac{1}{7}=0\\ \Rightarrow\left|x+\dfrac{4}{5}\right|=\dfrac{1}{7}\\ \Rightarrow\left[{}\begin{matrix}x+\dfrac{4}{5}=\dfrac{1}{7},\forall x+\dfrac{4}{5}\ge0\\x+\dfrac{4}{5}=-\dfrac{1}{7},\forall x+\dfrac{4}{5}< 0\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}x=-\dfrac{23}{35},\forall x\ge-\dfrac{4}{5}\left(N\right)\\x=-\dfrac{33}{35},\forall x< -\dfrac{4}{5}\left(N\right)\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}x=-\dfrac{23}{35}\\x=-\dfrac{33}{35}\end{matrix}\right.\)
\(b,\left|x-2\right|=x-2\\ \Rightarrow\left[{}\begin{matrix}x-2=x-2,\forall x-2\ge0\\x-2=2-x,\forall x-2< 0\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}x=0,\forall x\ge2\left(L\right)\\x=2,\forall x< 2\left(L\right)\end{matrix}\right.\\ \Rightarrow x\in\varnothing\)
1. Tam giác vuông
3. x= 9
4. sai đề òi bạn
5. 3 cm
6. số dư là 0
7. BAC= 75 độ
Câu 1. Tam giác vuông
Câu 2. không có giá trị nào
Câu 3. x=9
Câu 5. 3 cm
Câu 6. Số dư là 0
Câu 7. Góc BAC=75 độ
Câu 8. Không có giá trị nào cả
\(4-\left|x-\frac{1}{3}\right|=\frac{2}{3}\)
\(\Leftrightarrow\left|x-\frac{1}{3}\right|=4-\frac{2}{3}\)
\(\Leftrightarrow\left|x-\frac{1}{3}\right|=\frac{10}{3}\)
\(\Leftrightarrow\orbr{\begin{cases}x-\frac{1}{3}=\frac{10}{3}\\x-\frac{1}{3}=\frac{-10}{3}\end{cases}\Leftrightarrow}\orbr{\begin{cases}x=\frac{10}{3}+\frac{1}{3}\\x=\frac{-10}{3}+\frac{1}{3}\end{cases}\Leftrightarrow\orbr{\begin{cases}x=\frac{11}{3}\\x=-3\end{cases}}}\)
Vậy ...................
~ Hok tốt ~
#)Giải :
\(4-\left|x-\frac{1}{3}\right|=\frac{2}{3}\)
\(\Leftrightarrow\left|x-\frac{1}{3}\right|=\frac{10}{3}\)
\(\Leftrightarrow\orbr{\begin{cases}\left|x-\frac{1}{3}\right|>0\\\left|x-\frac{1}{3}\right|< 0\end{cases}\Rightarrow\orbr{\begin{cases}x=\frac{11}{3}\\-3\end{cases}}}\)
Vậy ..............................
\(2.\left|\frac{1}{2}-x\right|-\frac{1}{4}=\frac{7}{4}\)
=> \(2.\left|\frac{1}{2}-x\right|=\frac{7}{4}+\frac{1}{4}\)
=> \(2.\left|\frac{1}{2}-x\right|=2\)
=> \(\left|\frac{1}{2}-x\right|=2:2\)
=> \(\left|\frac{1}{2}-x\right|=1\)
=> \(\orbr{\begin{cases}\frac{1}{2}-x=1\\\frac{1}{2}-x=-1\end{cases}}\)
=> \(\orbr{\begin{cases}x=-\frac{1}{2}\\x=\frac{3}{2}\end{cases}}\)
Vậy ...
\(2.\left|\frac{1}{2}-x\right|-\frac{1}{4}=\frac{7}{4}\)
\(2.\left|\frac{1}{2}-x\right|=\frac{7}{4}+\frac{1}{4}=2\)
\(\left|\frac{1}{2}-x\right|=\frac{2}{2}=1\)
\(\Rightarrow\orbr{\begin{cases}\frac{1}{2}-x=1\\\frac{1}{2}-x=-1\end{cases}\Rightarrow\orbr{\begin{cases}x=\frac{1}{2}-1=-\frac{1}{2}\\x=\frac{1}{2}+1=\frac{3}{2}\end{cases}}}\)
Vậy x = \(-\frac{1}{2}\)hoặc x = \(\frac{3}{2}\)