SOLUTION: The product of three integers is 90. The second number is twice the first number. The third number is two more than the first number. What are the three numbers?

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Question 390325: The product of three integers is 90. The second number is twice the first number. The third number is two more than the first number. What are the three numbers?
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
The product of three integers is 90.
xyz = 90
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The second number is twice the first number.
y = 2x
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The third number is two more than the first number. What are the three numbers?
z = x+2
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Equation:
Substitute for y and for z and solve for "x":
x(2x)(x+2) = 90
2x^3+4x^2-90 = 0
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x^3 + 2x^2 - 45 = 0
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I graphed the cubic and found a solution at x = 3
Then y = 2x = 6
And z = x+2 = 5
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Check:
3*6*5 = 90
90 = 90
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Cheers,
Stan H.