a) x=800/7

b) x=8/33

c) x= 3/10

d) x=80

100 % đúng hết

a: \(B=\frac12-\left\lbrack\frac38+\left(-\frac74\right)\right\rbrack\)

\(=\frac12-\frac38+\frac74\)

\(=\frac48-\frac38+\frac{14}{8}=\frac{15}{8}\)

b: \(-\frac{4}{12}-\left(-\frac{13}{39}-0,25\right)+0,75\)

\(=-\frac13+\frac13+0,25+0,75\)

=0,25+0,75

=1

c: \(\frac12-\frac13+\frac{1}{23}+\frac16\)

\(=\left(\frac12-\frac13+\frac16\right)+\frac{1}{23}\)

\(=\left(\frac16+\frac16\right)+\frac{1}{23}=\frac13+\frac{1}{23}=\frac{26}{69}\)

d: \(\left(-\frac{13}{7}-\frac49\right)-\left(-\frac{10}{7}-\frac49\right)\)

\(=-\frac{13}{7}-\frac49+\frac{10}{7}+\frac49\)

\(=-\frac{13}{7}+\frac{10}{7}=-\frac37\)

e: \(\left(\frac78-\frac52+\frac47\right)-\left(-\frac37+1-\frac{13}{8}\right)\)

\(=\frac78-\frac52+\frac47+\frac37-1+\frac{13}{8}\)

\(=\frac{20}{8}-\frac52=0\)

f: \(-\frac37+\left(3-\frac34\right)-\left(2,25-\frac{10}{7}\right)\)

\(=-\frac37+3-\frac34-2,25+\frac{10}{7}\)

\(=\frac77+0,75-\frac34\)

=1
g: \(\left(\frac53-\frac37+9\right)-\left(2+\frac57-\frac23\right)+\left(\frac87-\frac43-10\right)\)

\(=\frac53-\frac37+9-2-\frac57+\frac23+\frac87-\frac43-10\)

\(=\left(\frac53+\frac23-\frac43\right)+\left(-\frac37-\frac57+\frac87\right)+\left(9-2-10\right)\)

\(=\frac33+7-10=1-3=-2\)

\(2^3.\left(2,25-\dfrac{1}{4}\right):\left(\dfrac{10}{3}-1\dfrac{1}{3}\right)^2\\ =8.\left(\dfrac{9}{4}-\dfrac{1}{4}\right):\left(\dfrac{10}{3}-\dfrac{4}{3}\right)^2\\ =8.2:2^2\\ =16:4\\ =4\)

\(B=\left(8-2,25+\dfrac{2}{7}\right)-\left(-6-\dfrac{3}{7}+1\dfrac{1}{4}\right)-\left(3+0,5-1\dfrac{2}{7}\right)\\ B=8-\dfrac{9}{4}+\dfrac{2}{7}+6+\dfrac{3}{7}-\dfrac{5}{4}-3-\dfrac{1}{2}+\dfrac{9}{7}\\ B=\left(8+6-3\right)+\left(-\dfrac{9}{4}-\dfrac{5}{4}\right)+\left(\dfrac{2}{7}+\dfrac{3}{7}+\dfrac{9}{7}\right)-\dfrac{1}{2}\)

\(B=11-\dfrac{7}{2}+2-\dfrac{1}{2}\\ B=\left(11+2\right)+\left(-\dfrac{7}{2}-\dfrac{1}{2}\right)\\ B=13-4\\ B=9.\)

a) \(\left(\frac{1}{3}.x\right):\frac{2}{3}=\frac{7}{4}:\frac{2}{5}\)

\(\left(\frac{1}{3}.x\right):\frac{2}{3}=\frac{35}{8}\)

\(\Rightarrow\frac{1}{3}.x=\frac{35}{8}.\frac{2}{3}\)

\(\Rightarrow\frac{1}{3}.x=\frac{35}{12}\)

\(\Rightarrow x=\frac{35}{12}:\frac{1}{3}\)

\(\Rightarrow x=\frac{35}{4}\)

Vậy \(x=\frac{35}{4}\)

a) x= \(\frac{35}{4}\)

4,5:0,3=2,25:0,1x

15=2,25 : 0,1x

2,25 :15 =0,1x

0,15 =0,1x

=> 0,15:0,1 

x= 1,5

x và y đều bằng nhau dù là nhân hay cộng. 

4,5 : 0,3 = 2,25 : (0,1.x)

   15       = 2,25 : (0,1.x)

    2,25 : 15 = 0,1.x

        0,15   = 0,1.x

      => x = 0,15 : 0,1

          x  = 1,5

TL:

4,5 : 0,3 = 2,25 : (0,1.x)

   15       = 2,25 : (0,1.x)

    2,25 : 15 = 0,1.x

        0,15   = 0,1.x

      => x = 0,15 : 0,1

          x  = 1,5

HT

\(7,1+\left(-5,25\right)-\left(-2,25+7,1\right)\)

\(=7,1-5,25+2,25-7,1\)

\(=\left(7,1-7,1\right)-\left(5,25-2,25\right)\)

\(=0+3\)

\(=3\)

Ủng hộ mk nha ^_-

1,5

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