CTET 2 Math and Science Dec 2018 Paper

Question : 38 of 120

Marks: +1, -0

Let

a, b, c

be three rational numbers, where

a=3/5,b=2/3

and

c=-5/6

. Which one of the following is true?

Solution:

We have,

a=3/5,b=2/3

and

c=-5/6

Check the option
(A)

a × (b + c) = b × (a + c)

3/5×(2/3-5/6)=2/3×(3/5-5/6)

3/5×(-1/6)=2/5 ×7/30

-1/10≠7/45

(B)

a ÷ (b + c) = b ÷ (a + c)

3/5÷(2/3-5/6)=2/3÷(3/5-5/6)

3/5÷(-1/6)=2/3 ÷(7/30)

-18/5=-60/21

-18/5≠-30/7

(c)

a + (b + c) = c + (a + b)

3/5+(2/3-5/6)=5/6+(3/5+2/3)

3/5-1/6=-5/6+19/15

{18-5}/30={-25+38}/30

13/30=13/30

Hence, option (C) is true.

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