CLASS 8 - REVISION 1 - RATIONAL NUMBERS AND LINEAR EQUATIONS IN ONE VARIABLE

 CLASS 8

REVISION 1

RATIONAL NUMBERS, LINEAR EQUATIONS IN ONE VARIABLE


1. Using appropriate properties, find 

    -2/5 x 4/7  +  1/7 x 3/2 -  2/3 x 4/7


2. Verify that - ( -x ) = x for 

     (i) x = 12/19

    (ii) x = -5/9


3. Find the additive inverse of

    (i) 12  (ii)  -15  (iii) 2/3   (iv)  7/-15  


4. Find the multiplicative inverse of

    (i) 1/5   (ii) -5   (iii)  -11/21   (iv) 8/-23


5. Multiply 1/2 by the reciprocal of -5/24.  What will be the value if the result is added to -17/5?


6.  Represent the following on the number line:

   (i) 6/5   (ii)  -1/8  (iii) 2/9   (iv)  -4/11


7. Write 5 rational numbers which are greater than 6.


8. Find a rational number between 1/2 and 1/3.


9. Find 5 rational numbers between -2/5 and 5/8.


10. Solve 3x + 15 = 27.

INTEGER RULES
INTEGER RULES



INTEGER RULES
EXAMPLES


11. Solve 2x/7 - 10 = 28


12. Solve 5 ( x-3 ) + 12 = - 24 - x


13. Find x given that 25 x = 5 ( x- 10 )


14. Solve for x:  0.25 (x + 22) = 2 x - 12


15. The sum of two numbers is 120. If one of the numbers is 30 more than the other, find the numbers.


16. Find ten rational numbers between 6/7 and 11/6.


17. Solve 12 x - 18 = - 30


18. Two sides of a triangle are 18 cm and 15 cm and its perimeter is 56 cm.  Find the third side of the triangle.


19.  Two numbers are in the ratio 7:4.  If they differ by 24, what are the numbers?


20. Three consecutive integers add up to 60.  What are these integers?


WHAT IS A LINEAR EQUATION


LINEAR EQUATION
LINEAR EQUATION IN ONE VARIABLE
DEFINITION WITH EXAMPLE















21. The number of boys and girls in a class are in the ratio 7:5.  The number of boys is 8 more than the number of girls.  What is the total class strength?


22. Fifteen years from now Ravi's age will be four times his present age.  What is Ravi's present age?


23. Solve 5t - 3 = 3t - 5


24. 2x/3 + 1 = 7x/15 + 3


25. A positive number is 5 times another number.  If 21 is added to both the numbers, then one of the new numbers becomes twice the other new number.  What are the numbers?


26.  Sum of the digits of a two-digit number is 9.  When we interchange the digits, it is found that the resulting new number is greater than the original number by 27.  What is the two-digit number?


27.  The ages of Rahul and Haroon are in the ratio 5:7.  Four years later the sum of their ages will be 56 years.  What are their present ages?


28. Half of a herd of deer are grazing in the field and three fourths of the remaining are playing nearby.  The rest 9 are drinking water from the pond.  Find the number of deer in the herd.

LCM
LEAST COMMON MULTIPLE


SOLVE THE FOLLOWING:


29.  n/2 - 3n/4 + 5n/6 = 21


30.  x + 7 - 8x/3  =  17/6  -  5x/2


31.  m - (m-1)/2  =  1- (m-2)/3


32.  15(y-4) - 2(y-9) + 5(y+6) = 0


33.  (7y+4)/(y+2) = -4/3


34. The denominator of a rational number is greater than its numerator by 8.  If the numerator is increased by 17 and the denominator is decreased by 1, the number obtained is 3/2. Find the rational number.


35. The ages of Hari and Harry are in the ratio 5:7.  Four years from now the ratio of their ages will be 3:4.  Find their present ages.


36.  Solve 0.25(4f - 3)  = 0.05 (10f - 9)

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