SOLUTION: a rectangle 15 cm by 30 cm is increased on all sides by the same amount. its area increased by 144cm2. by how much is each dimension increased?

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Question 663127: a rectangle 15 cm by 30 cm is increased on all sides by the same amount. its area increased by 144cm2. by how much is each dimension increased?
Answer by checkley79(3341) About Me  (Show Source):
You can put this solution on YOUR website!
15*30=4500 CM^2 ORIGINAL SIZE.
(15+X)(30+X)=450+144
4500+45X+X^2=594
X^2+45X+450-594=0
X^2+45X-144=0
(X-3)(X+48)=0
X-3=0
X=3 ANS.
PROOF:
(15+3)(30+3)=594
18*33=594
594=594