Question

Explain the whole lesson Operations on Rational numbers of grade 7... It's easy...

50 points ☺

Answer 1

what is rational number ??
★ any real number that can expressed in the form of P/Q where Q ≠ 0 is known as rational number .
e.g 4/5 , 0.4 , 1 etc are rational numbers .

★ addition of rational number :-
→ when denominator are same of two or more rational numbers , then addition
-----
ex :- add 2/3 and 5/3
here you see denominator same, so, addition ,
2/3 + 2/3 = (2+3)/3 = 5/3

→ addition when denominator are different . use LCM of denominator then proceed according to given example
example :-
add 2/5 + 4/10 here denominator of both are different so,
LCM of 5 and 10 = 10

now, 2/5 + 4/10 = ( 2×2 + 4 ×1)/10 = 8/10

★ subtraction of rational number :-
→ when denominator are same :- same rule apply . only change sign of addition to subtraction.
example :-
subtract 4/6 - 1/6 = ( 4 -1)/6 = 3/6
→ when denominator are different :-
use LCM of denominator of all given rational number .
example :- subtract 8/3 - 2/9 =?
LCM of 3 and 9 = 9
then , 8/3 - 2/9 = (8×3-2)/9 = 22/9

★multiplication of rational number :- it is very easy , when two more rational numbers given , and question want to multiply this then multiply numerator with numerator and denominator with denominator .
example :- multiply 2/3 , 4/5 , and 6/7
then ,
( 2× 4 × 6)/( 3 × 5 × 7)

=( 48)/( 105) = 48/105

★ division of rational number :-
Let a/b and c/d are two rational numbers , and question wants to divide this e.g a/b ÷ c/d

step 1 :- no change before division sign number ,

take reciprocal of a number which is found in after division sign , then ÷ convert into multiplication .
e.g a/b × 1/(c/d)
but we know, 1/(c/d) = d/c
so, a/b ×d/c

step 3 :- now use concept of multiplication.
e.g a/b × d/c = (a × d)/( b× c)

example :- divide 4/7 ÷ 3/8

step 1 :- 4/7 ÷ 3/8

step2 :- 4/7×1/(3/8)

= 4/7 ×8/3

step3 :- (4×8)/(7×3) = 32/21

Answer 2

Answer:

Step-by-step explanation:

what is rational number ??

any real number that can expressed in the form of P/Q where Q ≠ 0 is known as rational number .

e.g 4/5 , 0.4 , 1 etc are rational numbers .

addition of rational number :-

when denominator are same of two or more rational numbers , then addition

-----

ex :- add 2/3 and 5/3

here you see denominator same, so, addition ,

2/3 + 2/3 = (2+3)/3 = 5/3

addition when denominator are different . use LCM of denominator then proceed according to given example

example :-

add 2/5 + 4/10 here denominator of both are different so,

LCM of 5 and 10 = 10

now, 2/5 + 4/10 = ( 2×2 + 4 ×1)/10 = 8/10

subtraction of rational number :-

when denominator are same :- same rule apply . only change sign of addition to subtraction.

example :-

subtract 4/6 - 1/6 = ( 4 -1)/6 = 3/6

when denominator are different :-

use LCM of denominator of all given rational number .

example :- subtract 8/3 - 2/9 =?

LCM of 3 and 9 = 9

then , 8/3 - 2/9 = (8×3-2)/9 = 22/9

multiplication of rational number :- it is very easy , when two more rational numbers given , and question want to multiply this then multiply numerator with numerator and denominator with denominator .

example :- multiply 2/3 , 4/5 , and 6/7

then ,

( 2× 4 × 6)/( 3 × 5 × 7)

=( 48)/( 105) = 48/105