- #1
sin_city_stunner
- 8
- 0
1. The height,length and width of a small box are consecutive intergers with the height being the smallest of the three dimensions. If the length and width are increased by 1 cm each and the height is doubled, then the volume is increased by 120 cm^3. Find the dimensions of he original small box
2. v=lwh
3. I tried to appoach this two different ways but couldn't get either to work:
1. h = x
w = x+1
l= x+2
therefore (2x)(x+2)(x+3) = 120
2x^3 + 10x^2+12x-120 = 0
i tried to use the factor theroem to solve the equation but could not get it to work.
p{+-1,+-2,+-3...}
q{+-1,+-2}
p/q {+-1,+-1/2, +-2, +-3, +-3/2...}
I knowthat in order to solve the question, I am going to need to need to find the roots of the polynomial and therefore have to solve for x. The factor theroem indicates that if i plug in p/q into the above given equation, it will equal zero, and i can finish the question. The only problem i am having is determining which p/q value satisfies the equation. Another solution would be to factor, but i tried that and it ended up being..
2x^2(x+5) + 12(x-10) and since there are no more common factors, it cannot be taken any further. As a result, i am pretty sure i have to use the factor theorem, but i can't figure out what p/q value satisfies the equation
So then i tried (2x)(x+2)(x+3)= 120 + (x)(x+1)(x+2)
and got..
x^3+7x^2-10x-120 = 0
and tried to use factor theorem again but couldn't get it to work.
Thanks in advance for the help.
2. v=lwh
3. I tried to appoach this two different ways but couldn't get either to work:
1. h = x
w = x+1
l= x+2
therefore (2x)(x+2)(x+3) = 120
2x^3 + 10x^2+12x-120 = 0
i tried to use the factor theroem to solve the equation but could not get it to work.
p{+-1,+-2,+-3...}
q{+-1,+-2}
p/q {+-1,+-1/2, +-2, +-3, +-3/2...}
I knowthat in order to solve the question, I am going to need to need to find the roots of the polynomial and therefore have to solve for x. The factor theroem indicates that if i plug in p/q into the above given equation, it will equal zero, and i can finish the question. The only problem i am having is determining which p/q value satisfies the equation. Another solution would be to factor, but i tried that and it ended up being..
2x^2(x+5) + 12(x-10) and since there are no more common factors, it cannot be taken any further. As a result, i am pretty sure i have to use the factor theorem, but i can't figure out what p/q value satisfies the equation
So then i tried (2x)(x+2)(x+3)= 120 + (x)(x+1)(x+2)
and got..
x^3+7x^2-10x-120 = 0
and tried to use factor theorem again but couldn't get it to work.
Thanks in advance for the help.
Last edited: