SOLUTION: if the sides of a square are lengthened by 8 cm, the area becomes 225 cm^2. Find the length of a side of the original square. The length of a side of the original square is?

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Question 330426: if the sides of a square are lengthened by 8 cm, the area becomes 225 cm^2. Find the length of a side of the original square.
The length of a side of the original square is?
Found 2 solutions by solver91311, mananth:
Answer by solver91311(24713) About Me  (Show Source):
You can put this solution on YOUR website!


The new square has to have sides of 15, so the old square had sides of 15 - 8 = 7.


John

My calculator said it, I believe it, that settles it

Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!
let side =x
..
the increased length = x+8
Area = (x+8)(x+8)=225
x^2+16x+64=225
x^2+16x-159=0
find the roots of the equation by the quadratic formula
x=%28-b%2B-sqrt%28b%5E2-4%2Aa%2Ac%29%29%2F2a
x1=%28-b%2Bsqrt%28b%5E2-4%2Aa%2Ac%29%29%2F2a
a=1,b=16,c-159
x=%28-16%2Bsqrt%28256%2B4%2A1%2A159%29%29%2F2
x1=6.933 the original length of square
similarly x2 = -22.9 ignore