Question

A rectangular swimming pool is 8 meters long and 12 meters wide. A tile boarder of uniform width is to be built around the pool usinjg 120 square meters of tile. How wide should the boarder be? Round anser to the nearest hundredth.

Answer 1

Let x be the border width.
The area of border tile is
A = (8+2x)(12+2x)- 8*12
which is (outer area) - (pool area)
= 4x^2 + 40x + 96 - 96
= 4x^2+ 40 x = 120
Solve for x.
You can simplify that to
x^2 + 10x - 30 = 0
Factor that for the one positive root.

Answer 2

let the width of the border, note the spelling, be x m

then the whole pool area including the border is (8+2x)(12+2x) = 8(12) + 120
96 + 40x + 4x^2 = 216
x^2 + 10x -30 = 0

solve

I got x = 2.416 and some negative x number.

Answer 3

your correct