Simplifying the Expression (x+2)^3 - x(x+3)(x-3) - 12x^2 - 8
This article will guide you through simplifying the expression (x+2)^3 - x(x+3)(x-3) - 12x^2 - 8. We'll break down each step and explain the reasoning behind it.
Expanding the Expression
Let's start by expanding the expression step by step:
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(x+2)^3: This is a cube of a binomial. We can use the binomial theorem or simply multiply (x+2) by itself three times: (x+2)^3 = (x+2)(x+2)(x+2) = (x^2 + 4x + 4)(x+2) = x^3 + 6x^2 + 12x + 8
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x(x+3)(x-3): This is a product of three binomials. Notice that (x+3) and (x-3) form a difference of squares pattern: x(x+3)(x-3) = x(x^2 - 9) = x^3 - 9x
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-12x^2 - 8: This part remains unchanged for now.
Now, let's put everything together: (x+2)^3 - x(x+3)(x-3) - 12x^2 - 8 = (x^3 + 6x^2 + 12x + 8) - (x^3 - 9x) - 12x^2 - 8
Combining Like Terms
Finally, we can combine the like terms:
x^3 + 6x^2 + 12x + 8 - x^3 + 9x - 12x^2 - 8 = -6x^2 + 21x
Conclusion
Therefore, the simplified form of the expression (x+2)^3 - x(x+3)(x-3) - 12x^2 - 8 is -6x^2 + 21x.