Bài 3:
a: \(\dfrac{29}{14}=\dfrac{28+1}{14}=2+\dfrac{1}{14}\)
\(\dfrac{31}{15}=\dfrac{30+1}{15}=2+\dfrac{1}{15}\)
\(\dfrac{1}{14}>\dfrac{1}{15}\)
=>\(2+\dfrac{1}{14}>2+\dfrac{1}{15}\)
=>\(\dfrac{29}{14}>\dfrac{31}{15}\)
b: \(\dfrac{1212}{2323}=\dfrac{1212:101}{2323:101}=\dfrac{12}{23}\)
Bài 2:
a: \(\left|x-\dfrac{1}{5}\right|+\dfrac{1}{3}=\dfrac{1}{4}-\left|-\dfrac{3}{2}\right|\)
=>\(\left|x-\dfrac{1}{5}\right|=\dfrac{1}{4}-\dfrac{3}{2}-\dfrac{1}{3}=\dfrac{-1}{12}-\dfrac{3}{2}=\dfrac{-19}{12}\)
mà \(\left|x-\dfrac{1}{5}\right|>=0\forall x\)
nên \(x\in\varnothing\)
b: \(5\cdot3^x=7\cdot3^5-2\cdot3^5\)
=>\(5\cdot3^x=5\cdot3^5\)
=>\(3^x=3^5\)
=>x=5
Câu 1:
a: \(\dfrac{100}{123}:\left(\dfrac{3}{4}+\dfrac{7}{12}\right)+\dfrac{23}{123}:\left(\dfrac{9}{5}-\dfrac{7}{15}\right)\)
\(=\dfrac{100}{123}:\dfrac{9+7}{12}+\dfrac{23}{123}:\dfrac{27-7}{15}\)
\(=\dfrac{100}{123}:\dfrac{4}{3}+\dfrac{23}{123}:\dfrac{4}{3}\)
\(=\dfrac{3}{4}\cdot\dfrac{100}{123}+\dfrac{3}{4}\cdot\dfrac{23}{123}\)
\(=\dfrac{3}{4}\left(\dfrac{100}{123}+\dfrac{23}{123}\right)=\dfrac{3}{4}\)
b: \(7,8-4,7+\left(5,3-1,4\right)\)
\(=7,8-4,7+5,3-1,4\)
\(=\left(7,8-1,4\right)+\left(5,3-4,7\right)\)
\(=6,4+0,6=7\)
I. Trắc nghiệm
Câu 1. C
Câu 2. C
Câu 3. Bạn xem lại đề nhé (kết quả đúng:\(\dfrac{1}{10^{10}}\))
Câu 4. Bạn xem lại đề nhé (kết quả đúng: 992)
Câu 5. C
