3/5 - 1/5 : 0,25 - | - 2/5|
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A. 2/3 + 3/5 = 19/15
B. 4 và 1/4 - 0,25 = 4
C. 12 . 2 và 1/3 = 28
D. 8 và 2/7 + 4 và 3/5 + 1 và 5/7 + 5 và 2/5
= 58/7 + 23/5 + 12/7 + 27/5
= ( 27/5 + 12/5 ) + ( 58/7 + 12/7 )
= 39/5 + 10
= 89/5
= 39/5 + 70/7
\(1,\left[\left(-\dfrac{2}{5}\right)+\dfrac{1}{3}\right]-\left(\dfrac{3}{5}-\dfrac{1}{3}\right)=-\dfrac{2}{5}+\dfrac{1}{3}-\dfrac{3}{5}+\dfrac{1}{3}\\ =\left(-\dfrac{2}{5}-\dfrac{3}{5}\right)+\left(\dfrac{1}{3}+\dfrac{1}{3}\right)\\ =\dfrac{-2-3}{5}+\dfrac{1+1}{3}\\ =-\dfrac{5}{5}+\dfrac{2}{3}\\ =-1+\dfrac{2}{3}\\ =\dfrac{-3+2}{3}=-\dfrac{1}{3}\\ b,\left(\dfrac{3}{2}-\dfrac{3}{4}\right)-\left(0,25+\dfrac{1}{2}\right)\\ =\left(\dfrac{3}{2}-\dfrac{3}{4}\right)-\left(\dfrac{1}{4}+\dfrac{1}{2}\right)\\ =\dfrac{3}{2}-\dfrac{3}{4}-\dfrac{1}{4}-\dfrac{1}{2}\\ =\left(\dfrac{3}{2}-\dfrac{1}{2}\right)+\left(-\dfrac{3}{4}-\dfrac{1}{4}\right)\\ =\dfrac{3-1}{2}+\dfrac{-3-1}{4}\\ =\dfrac{2}{2}-\dfrac{4}{4}=1-1=0\)
1: =-2/5+1/3-3/5+1/3
=-1+2/3=-1/3
2: =3/2-3/4-1/4-1/2
=1-1=0
\(0,25.1\frac{3}{5}.\left(\frac{-5}{4}\right)^2:\left(\frac{-4}{7}\right)\)
\(=\frac{1}{4}.\frac{8}{5}.\frac{-5}{4}.\frac{-7}{4}\)
\(=\frac{1.8.\left(-5\right).\left(-7\right)}{4.5.4.4}\)
\(=\frac{280}{320}=\frac{7}{8}\)
\(\left(3\frac{2}{3}-2\frac{2}{5}\right).\left(\frac{-5}{3}\right)+3\left(2\frac{1}{2}:\frac{1}{2}\right)\)
\(=\left(\frac{17}{5}-\frac{12}{5}\right).\frac{-5}{3}+3\left(\frac{5}{2}.\frac{2}{1}\right)\)
\(=\frac{17-12}{5}.\frac{-5}{3}+3\left(\frac{5.2}{2.1}\right)\)
\(=1.\frac{-5}{3}+3.5\)
\(=\frac{-5}{3}+15\)
\(=\frac{-5+45}{3}\)
\(=\frac{40}{3}\)
\(a,\frac{1}{3}x+0.25=\frac{5}{7}\)
\(\Leftrightarrow\frac{1}{3}x=\frac{13}{28}\)
\(\Leftrightarrow x=\frac{39}{28}\)
vậy...
\(b,\frac{11}{12}x+0,25=\frac{5}{6}\)
\(\Leftrightarrow\frac{11}{12}x=\frac{7}{12}\)
\(\Leftrightarrow x=\frac{7}{11}\)
vậy.....
\(c,\left(\frac{-1}{3}\right)^2+\frac{2}{3}x=\frac{1}{4}\)
\(\Leftrightarrow\frac{1}{9}+\frac{2}{3}x=\frac{1}{4}\)
\(\Leftrightarrow\frac{2}{3}x=\frac{5}{36}\)
\(\Leftrightarrow x=\frac{5}{24}\)
vậy......
\(d,\left(3x+2\right)^3=-\frac{8}{125}\)
\(\Leftrightarrow3x+2=-\frac{2}{5}\)
\(\Leftrightarrow3x=-\frac{12}{5}\)
\(\Leftrightarrow x=-\frac{4}{5}\)
vậy.......
\(\frac{1}{3x}+0,25=\frac{5}{7}\)
\(\frac{1}{3x}+\frac{1}{4}=\frac{5}{7}\)
\(\frac{1}{3x}=\frac{13}{28}\)
\(3x=\frac{28}{13}\)
\(x=\frac{28}{39}\)
\(\frac{11}{12x}+0,25=\frac{5}{6}\)
\(\frac{11}{12x}+\frac{1}{4}=\frac{5}{6}\)
\(\frac{11}{12x}=\frac{7}{12}\)
\(x=\frac{11}{12}:\frac{7}{12}\)
\(x=\frac{7}{11}\)
\(\left(-\frac{1}{3}\right)^2+\frac{2}{3x}=\frac{1}{4}\)
\(\frac{1}{9}+\frac{2}{3x}=\frac{1}{4}\)
\(\frac{2}{3x}=\frac{5}{36}\)
\(x=\frac{2}{3}:\frac{5}{36}\)
\(x=\frac{5}{24}\)
\(\left(3x+2\right)^3=\left(-\frac{8}{125}\right)\)
\(\left(3x+2\right)^3=\left(-\frac{2}{5}\right)^3\)
\(\Rightarrow3x+2=-\frac{2}{3}\)
\(3x=-\frac{8}{3}\)
\(x=-\frac{9}{8}\)
Bài 1 :
\(\left(0.25\right)^5:\left(0,25\right)^3=\left(0,25\right)^2\)
a) \(3\dfrac{4}{5}:\dfrac{8}{5}=0,25:x\)
\(\Rightarrow\dfrac{19}{5}.\dfrac{5}{8}=\dfrac{x}{4}\)
\(\Rightarrow\dfrac{x}{4}=2\Rightarrow x=8\)
b) \(2x+\dfrac{3}{24}=3x-\dfrac{1}{32}\)
\(\Rightarrow x=\dfrac{1}{8}+\dfrac{1}{32}=\dfrac{5}{32}\)
c) \(\dfrac{13x-2}{2x+5}=\dfrac{76}{17}\)
\(\Rightarrow221x-34=152x+380\)
\(\Rightarrow69x=414\Rightarrow x=6\)
1) 2,75 - 5/6 × 2/5 = 2,75 - (5/6) × (2/5) = 2,75 - 1/3 = 2,75 - 0,33 = 2,42
2) 1,25 - (5/6 - 0,75) - 3/5 = 1,25 - (5/6 - 0,75) - 3/5 = 1,25 - (5/6 - 3/4) - 3/5 = 1,25 - (5/6 - 9/12) - 3/5 = 1,25 - (10/12 - 9/12) - 3/5 = 1,25 - 1/12 - 3/5 = 1,25 - 0,08 - 0,6 = 1,25 - 0,68 = 0,57
3) 4/9 × 0,75 + 8/5 + 3,125 = (4/9) × 0,75 + 8/5 + 3,125 = 0,44 + 8/5 + 3,125 = 0,44 + 1,6 + 3,125 = 0,44 + 4,725 = 5,165
4) 1,125 - 4/7 - 0,12 = 1,125 - (4/7) - 0,12 = 1,125 - 0,57 - 0,12 = 0,435 - 0,12 = 0,315
5) (1/3 + 0,4) × 3,5 + (1/6 + 0,75) × 6/5
\(a,=\dfrac{5}{3}-\dfrac{2}{7}+\dfrac{6}{5}=\dfrac{271}{105}\\ b,=\dfrac{1}{4}+\dfrac{3}{5}-\dfrac{1}{8}+\dfrac{2}{5}-\dfrac{5}{4}=1-1-\dfrac{1}{8}=-\dfrac{1}{8}\)
1a) \(\dfrac{5}{3}-\dfrac{2}{7}+1,2=\dfrac{5}{3}-\dfrac{2}{7}+\dfrac{6}{5}=\dfrac{175}{105}-\dfrac{30}{105}+\dfrac{126}{105}=\dfrac{107-30+126}{105}=\dfrac{203}{205}\)
\(\frac{3}{5}-\frac{1}{5}\div0,25-\left|-\frac{2}{5}\right|\)
\(=\frac{3}{5}-\frac{1}{5}\times4-\frac{2}{5}\)
\(=\frac{3}{5}-\frac{4}{5}-\frac{2}{5}\)
\(=-\frac{3}{5}\)