SOLUTION: Can you find three consecutive integers whose product is 5 greater than the cube of the middle integer?

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Question 894661: Can you find three consecutive integers whose product is 5 greater than the cube of the middle integer?

Answer by Theo(13342)   (Show Source): You can put this solution on YOUR website!
the number is x = -6

-6*-5*-4 = -120

(-5)^3 + 5 = -125 + 5 = -120

the number checks out ok.

the process is as follows:

the 3 numbers are x, x+1, x+2

(x+1)^3 + 5 = x^3 + 3x^2 + 3x + 1 + 5 which is equal to:

x^3 + 3x^2 + 3x + 6

x*(x+1)*(x+2) is equal to x^3 + 3x^2 + 2x

you get:

x^3 + 3x^2 + 2x = x^3 + 3x^3 + 3x + 6

subtract (x^3 + 3x^2 + 2x) from both sides of this equation to get:

0 = x + 6

solve for x to get x = -6

the rest is confirmation that was done up top.





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