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:
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.
ddiiyya:
thankyou
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