Question

find the speed of a super fast train by increasing the speed of a train by 30 km per hour and making it super fast so that the time to cut the distance between two places at a distance of 1200 km is reduced by 2 hr.

step by step explanation plz fast
don't type any absurd comments ​or else I have to report

Answer 1

Step-by-step explanation:

hey purvi the above sum is of quadratic equation

so now let the speed of super fast train be x km/hr

so then we know that speed=distance/ time

so original time is (1200 upon x ) hours

now when speed is increased by 30 km per hour

time taken is 1200/x+30 hours

so our equation is 1200/x+30=1200/x-2 so

then now

it can be also written as 1200/x+30 - 1200/x=2

then take 1200 as common you would be getting

1200 (1 upon x+30 -1 upon x)=2

solve it you would be getting

1200 (30 upon x square+30 x)=2

bring it in quadratic form you get

2x square+60 x-36000 =0

dividing it in on 2 both sides

so x square+30x-18000=0

solve it by formula method

so you would be getting discriminant ie delta value as 72900

so I hope u know that formula

x=-b+- under root of delta upon 2

so substitute delta b and a values in it

you get x=120 or x=-150

now since speed is never negative x=-150 is absurd

so x=120

thus original speed is 120 km/hr

I hope this helped you a lot

u can also ask me more questions

maths is my passion second love and my leisure time as well