SOLUTION: The volume in cubic metres of water in an aquarium is given by the polynomial v(x)=x^3-16x^2+79x-120.If the dept in metres can be represented by x-3, what are the possible dimensio

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Question 751370: The volume in cubic metres of water in an aquarium is given by the polynomial v(x)=x^3-16x^2+79x-120.If the dept in metres can be represented by x-3, what are the possible dimensions of the rectangular aquarium in terms of x if the aquarium holds 70 cubic metres (70 000 litres)
The answer is 7 by 5 by 2 i need the steps though!!
ANY HELP APPRECIATED!

Answer by josgarithmetic(39618) About Me  (Show Source):
You can put this solution on YOUR website!
If x-3 is actually a root for v(x), then you could more easily factor the function. Try synthetic division by (x-3). See what this allows you to do. I have not tried all this yet but it might be all you need.
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I'm not getting anything like what you say is the answer. That "x-3" seems to be no help. At holding 70 cubic meters, v=x%5E3-16x%5E2%2B79x-120=70;
x%5E3-16x%5E2%2B79x-120-70=0
x%5E3-16x%5E2%2B79x-190=0
Trying synthetic division according to Factor Theorem %28x-10%29%28x%5E2-6x%2B19%29=0 so a rational root is 10. The quadratic factor has imaginary parts.
x=10 if this aquarium holds 70 m^3, and the depth is x-3=10-3=7 meters.