math

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the width of a square-based storage tank is 3m less than its height. The tank has a capacity of 20m^3. If the dimensions are integer values in metres, what are they?

  • math -

    each side of base --- x m
    height --- x+3

    x^2(x+3) = 20
    x^3 + 3x^2 = 20

    since the solution is to be an integer, try
    x=1 , 1 + 3 = 20 , no
    x=2, 8 + 3(4) = 20 ,YES

    well, that was easy.
    base is 2 m by 2, with a height of 5

  • math -

    but its less than 3

  • math -

    base is 2 m by 2 m
    height is 2+3 = 5 m

    volume = 2x2x5 = 20

    My answer is correct.

    what do you mean by "but its less than 3"

  • math -

    oh nothing , i get it now, thank you :)

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