Question

an aeroplane takes 5 hours less to journey for the 500 km if its speed is increased by 10 km per hour it intial speed. find the speed of intial speed of a plane​

Answer 1

Answer:

⇒ Let the usual speed be xkm/hr

According to the question,

⇒

x

1200

−

100+x

1200

=1

⇒

x(100+x)

1200(100+x)−1200x

=1

⇒ 120000+1200x−1200x=100x+x

2

⇒ 120000=100x+x

2

⇒ x

2

+100x−120000=0

⇒ x

2

+400x−300x−120000=0

⇒ x(x+400)−300(x+400)=0

⇒ (x+400)(x−300)=0

⇒ x=−400 and x=300

Speed can not be negative.

∴ Original speed =300km/hr

Answer 2

Let the usual speed be xkm/hr

According to the question,

⇒

x

1200

−

100+x

1200

=1

⇒

x(100+x)

1200(100+x)−1200x

=1

⇒ 120000+1200x−1200x=100x+x

2

⇒ 120000=100x+x

2

⇒ x

2

+100x−120000=0

⇒ x

2

+400x−300x−120000=0

⇒ x(x+400)−300(x+400)=0

⇒ (x+400)(x−300)=0

⇒ x=−400 and x=300

Speed can not be negative.

∴ Original speed =300km/hr

do same like this