SOLUTION: a rectangle 15cm by 30 cm is increased by the same amount. Its area is increased by 144cm^2. By how much is each dimension increased?

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Question 398269: a rectangle 15cm by 30 cm is increased by the same amount. Its area is increased by 144cm^2. By how much is each dimension increased?
Answer by robertb(5830) About Me  (Show Source):
You can put this solution on YOUR website!
(15+x)(30 + x) = 15*30 + 144
450+%2B+45x+%2B+x%5E2++=594
x%5E2+%2B+45x+-+144+=+0 ==> (x -3)(x + 48) = 0
==> x = 3, -48 ==> x = 3
==> Width is increased by (3/15)*100% = 20%, and the
length is increased by (3/30)*100% = 10%.