Page 22 - SM inner class 7.cdr

9
æ 5 ö æ ö 25 4
Ex am ple 20. = Solve ç ÷ ¸ ç ÷ = ´
è 8ø è ø 5 3
7
So lu tion : The pro ceed is as Divide; multiplication of numerators by
5 9 multiplication of denominators and we get;
= ¸ (25 ´ )
4
8 7 =
3
(5 ´ )
æ 5 ö æ 9 ö æ 7 ö
Multiply ç ÷ with reciprocal of ç ÷ which is ç ÷
è 8ø è 7ø è 9ø Solve the brackets and we get;
and we get; 100 20 2
= = = 6
5 7 15 3 3
= ´
8 9 9 6
Ex am ple 22. = Solve ¸
Divide; multiplication of numerators by 10 7
multiplication of denominators and we get; So lu tion : The pro ceed is as :
(5 ´ ) 9 6
7
= = ¸
(8 ´ ) 10 7
9
9 6 7
Solve the brackets and we get; Multiply with reciprocal of which is and
35 10 7 6
= we get;
72
9 7
25 3 = ´
Ex am ple 21. Solve ¸ 10 6
5 4
Divide; multiplication of numerators by
Solution : The pro ceed is as :-
multiplication of denominators and we get;
25 3
7
= ¸ (9 ´ )
5 4 =
(10 ´ )
6
25 3 4
Multiply with reciprocal of which is and
5 4 3 Solve the brackets and we get;
we get; 63 3
= =1
60 60
E xercise 2.3

1. Find the re cip ro cal of each of the fol low ing frac tions :
5 8 13 3
(a) (b) (c) (d)
8 7 7 4
2. Di vide the fol low ing :
3 7 1 4
(a) 18 ¸ (b) 8 ¸ (c) 3 2¸ (d) 5 3¸
4 3 3 7
3. Eval u ate :
2 7 4 4
(a) ¸ 3 (b) ¸ 5 (c) ¸
5 8 9 5

Word Problems on Fractions So lu tion : Ac cord ing to the prob lem,
4 4
Ex am ple 23. of a number is 84. Find the of Number = 84
7 7
num ber.

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Mathematics In Focus - 7