Question

The length of a rectangle is decreased by r % and the breadth is increased by (r+5) %. Find the r, if the area of the rectangle is unalerted.​

Answer 1

Answer:

20

Step-by-step explanation:

Let original length = x and original breadth = y

Then,

Original area = xy

New area :

=[(100−r)100×x][(105+r)100×y]=[(10500−5r−r210000)xy]∴(10500−5r−r210000)xy=xy⇒r2+5r−500=0⇒(r+25)(r−20)=0⇒r=20