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Chapter - 1

1)

Find an integer which when multiplied by -1 and divided by -9 results into reciprocal of that integer.

Solution:

Integer ×( -1 )

( -9 )

=

1

Integer

-(Integer × 1 )

( -9 )

=

1

Integer

 Integer x Integer = 3 x 3

 Integer = 3 

2)

A railway engine starts shunting wagons by first going 1000m   north of railway station. It   reverses and travels 1250m south and then it   again moves 600m north. Finally moving 800m south it comes to rest. How far is the engine from the station and in which direction?

Solution: (+ denoted northdirection and – denotes south direction.)​

= (+1000) + (-1250) + 600 (-800)

 

= -(1250 -1000) + 600 + (-800)

​

= -250 +600 + (-800)​

​

= -(800 -350) = -450

​

Hence, the position of the engine is 450m south from the station.

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