Có: ∣\(\sqrt{x}\)-1∣-3=1

      ∣\(\sqrt{x}\)-1∣=4 

_Nếu ∣\(\sqrt{x}\)-1∣=\(\sqrt{x}\)-1 thì: 

     \(\sqrt{x}\)-1=4

     \(\sqrt{x}\)=5

     x=\(5^2\)=25

  _Nếu ∣\(\sqrt{x}\)-1∣=-(\(\sqrt{x}\)-1)=-\(\sqrt{x}\)+1 thì:

      -\(\sqrt{x}\)+1=4

          -\(\sqrt{x}\)=3

             \(\sqrt{x}\)=-3

                x=\(\left(-3\right)^2\)

                x=9

Vậy x=25 hoặc x=9

Bài giải

Số tiền lãi là:

2062400-2000000=62400(đồng)

Lãi suất hàng tháng là:

62400:6=10400(đồng)

Đáp số: 10400 đồng

a)0,(3)+3\(\dfrac{1}{2}\)+0,4(2)=\(\dfrac{1}{3}\)+\(\dfrac{7}{2}\)+\(\dfrac{19}{45}\)=\(\dfrac{30}{90}\)+\(\dfrac{315}{90}\)+\(\dfrac{38}{90}\)=\(\dfrac{383}{90}\)

b)\(\dfrac{4}{9}\)+\(\dfrac{1219}{990}\)-\(\dfrac{13}{99}\)=\(\dfrac{440}{990}\)+\(\dfrac{1219}{990}\)-\(\dfrac{130}{990}\)=\(\dfrac{1529}{990}\)=\(\dfrac{139}{90}\)

a) Nếu x=0,5 thì:

    A=\(0,5^2\)-2.\(0,5\)+3

    A=0.5.(0,5-2)+3

    A=0,5.(-1,5)+3

    A=-0,75+3

    A=2,25

    Nếu x=-0,5 thì:

    A=\(\left(-0,5\right)^2\)-2.\(\left(-0,5\right)\)+3

    A=-0,5.(-0,5-2)+3

    A=-0,5.(-2,5)+3

    A=1,25+3

    A=4,25

Vậy A=2,25 hoặc A=4,25

b) Nếu x=\(\dfrac{1}{3}\) thì:

   B=\(\dfrac{1}{3}\)-3+1-3.\(\dfrac{1}{3}\)

   B=\(\dfrac{1}{3}\).(1-3)-3+1

   B=\(\dfrac{1}{3}\).(-2)-2

   B=(-2).(\(\dfrac{1}{3}\)+1)

   B=(-2).\(\dfrac{4}{3}\)

   B=\(\dfrac{-8}{3}\)

   Nếu x=\(\dfrac{-1}{3}\) thì:

   B=\(\dfrac{-1}{3}\)-3+1-3.\(\dfrac{-1}{3}\)

   B=\(\dfrac{-1}{3}\).(1-3)-3+1

   B=\(\dfrac{-1}{3}\).(-2)-2

   B=(\(\dfrac{-1}{3}\)+1).(-2)

   B=\(\dfrac{2}{3}\)(-2)

   B=\(\dfrac{-4}{3}\)

Vậy B=\(\dfrac{-8}{3}\) hoặc B=\(\dfrac{-4}{3}\)

a) Có: m=\(\sqrt{25+9}\)=\(\sqrt{34}\)=5,83095...

           n=\(\sqrt{25}\)+\(\sqrt{9}\)=5+3=8

    Vì 5,83095...<8 nên m<n

    Vậy m<n

b) Có: y=\(\sqrt{49-16}\)=\(\sqrt{33}\)=5,744...  

           z=\(\sqrt{81}\)-\(\sqrt{9}\)=9-3=6

    Vì 5,744...<6 nên y<z

   Vậy y<z

a) A=\(\sqrt{36}\).3\(\sqrt{4}\)-\(\sqrt{\dfrac{1}{9}}\)+2

    A=6.3.2-\(\dfrac{1}{3}\)+2

    A=36-\(\dfrac{1}{3}\)+\(\dfrac{6}{3}\)

    A=\(\dfrac{108}{3}\)-\(\dfrac{1}{3}\)+\(\dfrac{6}{3}\)

   A=\(\dfrac{113}{3}\) 

Vậy A=\(\dfrac{113}{3}\)

b) B=\(\sqrt{\dfrac{1}{9}+\dfrac{1}{16}}\)

    B=\(\sqrt{\dfrac{25}{144}}\)

    B=\(\dfrac{5}{12}\)

Vậy B=\(\dfrac{5}{12}\)

c) C=\(\sqrt{\dfrac{1}{9}}\)+\(\sqrt{\dfrac{25}{36}}\)-\(\sqrt{\dfrac{49}{81}}\):\(\sqrt{\dfrac{441}{324}}\)

    C=\(\dfrac{1}{3}\)+\(\dfrac{5}{6}\)-\(\dfrac{7}{9}\):\(\dfrac{7}{6}\)

    C=\(\dfrac{2}{6}\)+\(\dfrac{5}{6}\)-\(\dfrac{2}{3}\) 

    C=\(\dfrac{2}{6}\)+\(\dfrac{5}{6}\)-\(\dfrac{4}{6}\)

    C=2

Vậy C=2

d) D=\(\sqrt{\left(\dfrac{-2}{5}\right)^2}\)+\(\sqrt{1,44}\)-\(\sqrt{256}\)

    D=\(\dfrac{2}{5}\)+\(\dfrac{6}{5}\)-16

    D=\(\dfrac{8}{5}\)-\(\dfrac{80}{5}\)

    D=\(\dfrac{-75}{5}\)=-15

Vậy D=-15

Bài giải

Chu vi mảnh vườn là:

(5,5+3,75).2=18,5(m)

Số khóm hoa cần trồng là:

18,5:\(\dfrac{1}{4}\)=74(khóm)

                 Đáp số: 74 khóm hoa

a)\(\dfrac{1}{5}\)+\(\dfrac{4}{5}\):x=0,75                                                                        

         \(\dfrac{4}{5}\):x=0,75-\(\dfrac{1}{5}\)

         \(\dfrac{4}{5}\):x=\(\dfrac{11}{20}\)

             x=\(\dfrac{4}{5}\):\(\dfrac{11}{20}\)  

             x=\(\dfrac{16}{11}\)   

    Vậy x=\(\dfrac{16}{11}\)

b)x+\(\dfrac{1}{2}\)=1-x

  x+x  =1-\(\dfrac{1}{2}\)  

       2x=\(\dfrac{1}{2}\)

         x=\(\dfrac{1}{2}\):2

         x=\(\dfrac{1}{4}\)

     Vậy x=\(\dfrac{1}{4}\)

a)\(\dfrac{2}{3}\).\(\dfrac{5}{4}\)-\(\dfrac{3}{4}\).\(\dfrac{2}{3}\)=\(\dfrac{2}{3}\).(\(\dfrac{5}{4}\)-\(\dfrac{3}{4}\))=\(\dfrac{2}{3}\).\(\dfrac{1}{2}\)=\(\dfrac{1}{3}\)

b)2.(\(\dfrac{-3}{2}\))\(^2\)-\(\dfrac{7}{2}\)=2.\(\dfrac{9}{4}\)-\(\dfrac{7}{2}\)=\(\dfrac{9}{2}\)-\(\dfrac{7}{2}\)=\(\dfrac{2}{2}\)=1

c)-\(\dfrac{3}{4}\).5\(\dfrac{3}{13}\)-0,75.\(\dfrac{36}{13}\)=\(\dfrac{-3}{4}\).\(\dfrac{68}{13}\)+\(\dfrac{-3}{4}\).\(\dfrac{36}{13}\)=\(\dfrac{-3}{4}\).(\(\dfrac{68}{13}\)+\(\dfrac{36}{13}\))=\(\dfrac{-3}{4}\).\(\dfrac{104}{13}\)=-6