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a: \(\Leftrightarrow\left(x-\dfrac{2}{5}\right):\dfrac{3}{2}=-\dfrac{5}{4}+\dfrac{5}{2}=\dfrac{5}{4}\)
\(\Leftrightarrow x-\dfrac{2}{5}=\dfrac{5}{4}\cdot\dfrac{3}{2}=\dfrac{15}{8}\)
hay x=91/40
b: \(\Leftrightarrow\left(2.5x-3.6\right)=-1\cdot\dfrac{12}{7}=\dfrac{-12}{7}\)
=>2,5x=66/35
hay x=132/175
c: \(\Leftrightarrow\left(\dfrac{15}{4}-2x\right)=\dfrac{19}{9}:\dfrac{4}{3}=\dfrac{19}{9}\cdot\dfrac{3}{4}=\dfrac{19}{12}\)
=>2x=15/4-19/12=45/12-19/12=26/12
=>x=13/12
\(4\frac{1}{2}:\left(2,5-\frac{33}{4}\right)+\left(-\frac{1}{2}\right)^2\)
= \(\frac{9}{2}:\left(-\frac{23}{4}\right)+\frac{1}{4}\)
= \(-\frac{18}{23}+\frac{1}{4}\)
= \(-\frac{49}{92}\)
1) \(A=\left|-3,75\right|-\frac{31}{2}+\frac{1}{4}\)
\(A=\frac{15}{4}-\frac{31}{2}+\frac{1}{4}\)
\(A=\left(-\frac{47}{4}\right)+\frac{1}{4}\)
\(A=-\frac{23}{2}.\)
2) \(A=\frac{3}{2}-\left(-3\right)-\left(2,5-3\right)-\left[1,5+\left(-2,5\right)\right]\)
\(A=\frac{3}{2}-\left(-3\right)-\left(-\frac{1}{2}\right)-\left(-1\right)\)
\(A=\frac{9}{2}-\left(-\frac{1}{2}\right)-\left(-1\right)\)
\(A=5-\left(-1\right)\)
\(A=6.\)
Chúc bạn học tốt!
1) \(A=\left|-3.75\right|-\frac{31}{2}+\frac{1}{4}\)
\(\Leftrightarrow A=3.75-\frac{62}{4}+\frac{1}{4}\)
\(\Leftrightarrow A=\frac{15}{4}-\frac{62}{4}+\frac{1}{4}\)
\(\Leftrightarrow A=\frac{15-62+1}{4}\)
\(\Leftrightarrow A=-\frac{46}{4}=-\frac{23}{2}\)
Vậy : \(A=-\frac{23}{2}\)
2) \(A=\frac{3}{2}-\left(-3\right)-\left(2,5-3\right)-\left[1,5+\left(-2,5\right)\right]\)
\(\Leftrightarrow A=\frac{3}{2}+3-\left(-0,5\right)-\left(-1\right)\)
\(\Leftrightarrow A=1,5+3+0,5+1\)
\(\Leftrightarrow A=6\)
Vậy : \(A=6\)
2,5 giờ : 4 + 18,75 giờ : 4 + 2\(\dfrac{3}{4}\) giờ : 4
= 2,5 giờ : 5 + 18,75 giờ : 4 + 2,75 giờ :4
= ( 2,5 giờ + 18,75 giờ + 2,75 giờ) : 4
= 24 giờ : 4
= 6 giờ
`(2/3-0,25+2)-(2-5/2+1/4)-(2,5-1/3)`
`= 2/3 -1/4 +2-2+ 5/2 -1/4 -5/2 +1/3`
`= (2/3 +1/3) +(-1/4 -1/4) + (2-2) + (5/2-5/2)`
`= 3/3 + (-1/2) + 0 + 0`
`= 1 +(-1/2)`
`= 1/2`
\(\left(\dfrac{2}{3}-0,25+2\right)-\left(2-\dfrac{5}{2}+\dfrac{1}{4}\right)-\left(2,5-\dfrac{1}{3}\right)\\ =\dfrac{2}{3}-0,25+2-2+\dfrac{5}{2}-\dfrac{1}{4}-2,5+\dfrac{1}{3}\\ =\left(\dfrac{2}{3}+\dfrac{1}{3}\right)+\left(\dfrac{5}{2}-2,5\right)+\left(2-2\right)+\left(-\dfrac{1}{4}-0,25\right)\\ =\dfrac{3}{3}+\left(2,5-2,5\right)+0+\left(-\dfrac{1}{4}-\dfrac{1}{4}\right)\\ =1+0+0+\left(-\dfrac{1}{2}\right)=\dfrac{1}{2}\)