Math, asked by Javeriarafi, 1 year ago

the area of a small rectangular plot is 84m square if the difference between its length and breadth is 5m .find it's perimeter

Answers

Answered by anamikakumari7oy7kfe

125

Let L =x
then B=x-5
area = (x) (x-5)=84
or x2-5x-84=0
solving it we get x= 12 and -7
taking x = 12 we get
L=12 and B=12-5 =7
P=2(L+B) = 2(12+7) =2(19) =38m ans.

Answered by zeborg

Hope this helps. Ask if you have any doubts.
Fix: The 2nd last step of quadratic solution has -7(b+12) and not -7(b-12).
It's metres at the end, not centimetres.

Attachments:

Javeriarafi: can u plz tell me how 12b and 7b came plz

zeborg: When you find the LCM of 84, you will get 2x2x3x7. Now you need to perform a calculation such that the product any two numbers equals the product of constant term (-84) and the 1st term (b²); and their sum equals the middle term (5b). On multiplying 12b and -7b, we get -84b² which was required, and their sum also gives us the middle term, that is 5b.

Javeriarafi: tq once again

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