Question

a rectangular playground is 420 sq.m. if it's length is increased by 7 m and breadth is decreased by 5 meters‚ the area still remains the same. find the length and breadth of the playground.
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Answer 1

Answer:

Step-by-step:

let the length be l and the breadth be b.

area of the reactangle is l*b=420

l=420/b.

and if length becomes l+7 and breadth becomes b-5 the area still remains same.

now, the area of rectangle is (l+7)*(b-5)=420

l*b+7b-5l-35=420

but l*b=420

they gets cancelled.

7b-5l-35=0

l=420/b

so 7b-5*420/b-35=0

multiply by b on both sides we get

7b^2-35b-2100=0

solving this quadratic equation we get

b=15 or b=-20

but distance cant be -ve.

so b cant be -20.

so b=15m.

l=420/b

l=28m.