# Thread: check my work w/ this word problem

1. ## check my work w/ this word problem

ok so i'm not sure if my answers are right

An open box is to be formed by cutting four identical squares from the coners of a sheet of metal 20cm by 20cm, and folding up the metal to form sides. the capasity of the box must be $588cm^3$. what is the side length of the squares?

this is what i got

let x be the length of the missing sides

x(20-2x)(20-2x)=588
$4x^3-80x^2+400x-588=0$
$4(x^3-20x^2+100x-147)=0$

where is got a factor of (x-3)

and was left with $x^2-17x+49$

wich gave me x=15.44 or x=1.55

so the length can be 3cm, 15.44cm, or 1.55cm?

2. Originally Posted by extraordinarymachine
ok so i'm not sure if my answers are right

An open box is to be formed by cutting four identical squares from the coners of a sheet of metal 20cm by 20cm, and folding up the metal to form sides. the capasity of the box must be $588cm^3$. what is the side length of the squares?

this is what i got

let x be the length of the missing sides

x(20-2x)(20-2x)=588
$4x^3-80x^2+400x-588=0$
$4(x^3-20x^2+100x-147)=0$

where is got a factor of (x-3)

and was left with $x^2-17x+49$

wich gave me x=15.44 or x=1.55

so the length can be 3cm, 15.44cm, or 1.55cm?
$x = 3$

$x^2-17x+49 = 0$

$x = \frac{17 \pm \sqrt{93}}{2}$

$x= 13.322$

$x = 3.678$

is it physically possible for $x = 13.322$ ???