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Class 8 RS Aggarwal Math Solutions

Contents

3.        Square and Square root Ex 3A, B, C, D, E, F, G

4.        Cube and cube roots Ex 4A, B, C

 

 

 

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Q5.             = 3.14

                                                3  9.85 96  ( 3.14    

                                                3     9                          

                                           61        x 85

                                              1                     61                                  

                                          624         2496

                                                         2496

                                                           xx         

                                   

Q6.           = 3.17

                                                3  10.0489  ( 3.17   

                                                3     9                          

                                           61        104

                                              1                     61                                  

                                          627         4389

                                                         4389

                                                           xx         

 

 

 

 

Q12.  Let the side of square = y. now, we know area of square = (y)2, and area of l

ATQ, area of square = area of rectangle.

46.24m = y2   =>  y =    = 6.8. Hence, each side of a square = 6.8m.

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EXERCISE -3G

                           

 

Q9.         =     =     .

Q10.       =     =     =  2 x 7 x 9 = 126.

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EXERCISE-4C

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[FROM OLD BOOK]

Find THE Cube root of

1.                   343                                                                                        

Ans.       we have  =    =   7.                                                           

2.                   2744

Ans.       we have     =                               = 2 x7  = 14.                                                                                                                                                                                                   

3.                   10648

Ans.       we have     =       = 22.

4.                   17576

Ans.       we have     =      = 26.

5.                   4913

Ans.       we have       =                             =  17.

6.                   27000

Ans.       we have     =          =  30.

7.                   91125

Ans.       Hints; 5x5x5x9x9x9 = 45.

8.                   50653

Ans.       Hints;  37x37x37  = 37.

9.                    

Ans.       we have          =      =  

  

10.                

Ans.              we have      =-    =      =  .                            

11.                                                                                                                                                               

Ans.              we have      =    -    = -    =   .

 

12.                4     

Ans.             we have    =      =       = .                                                                                                                                                                                                                     

13.               1.331

Ans.       we have    =   =  1.1

14.               0.003375

Ans.       we have    =   =   0.15

 

15.               & 16 similar  (try it yourself)

 

17.          -8000

Ans.       we have  = -    =  -20.

 

16.               18, 19,20  similar  (try it yourself)            

                               

21.          i) Show that        x   =

 

Ans.        =   =  2.   And   =   =  9.    x   = 2 x 9 =18.

               

                 =  = 2 x 9 = 18. Hence,  x   = .   

 

ii)            similar  (Do it yourself)

iii)          (DIY)

iv)           (DIY)

 

Q22.       The vol. of a cubical box is 13.824 cubic metres. Find the length of each side of the box. solution:          

                We have , volume of a cubical box = 13.824 cm3                 =>(edge)3 =   

               

                 edge =     = 

 

=               =    =  2.4 m 

 

 So. The length of each side of the box = 2.4m.

 

 23.         Resolving 26244 into prime factors, we find that

                 26244 = 3x3x3 x 3x3x3 x 6x6       

So, we will multiply by 6 for a perfect cube = 6 x 26244 = 157464

Now, cube root of product = =

= 2 x 3 x 9 = 54.

 

  24.        Resolving 88209 into prime factors, we find that

                88209 = 3x3x3 x 3x3x3 x 121        

                So, we will divide by 121 for a perfect cube =    = 729

                Now, cube root of quotient is =     =        = 9.

 

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