Question 490670: I really need help please with this...
Andrew factored the expression -12x^3-28x^2-36x as -4x(3x^2-7x+9). But when Melissa applied the distributive law and multiplied out -4x(3x^2-7x+9), she got -12x^3+28x^2-36x ; thus, Andrew’s solution does not appear to check. Why is that? Please help Andrew to understand this better. Explain your reasoning and correctly factor the original expression, if possible. If the expression is prime, so state.
Answer by Alan3354(69443)   (Show Source):
You can put this solution on YOUR website! Andrew factored the expression -12x^3-28x^2-36x as -4x(3x^2-7x+9). But when Melissa applied the distributive law and multiplied out -4x(3x^2-7x+9), she got -12x^3+28x^2-36x ; thus, Andrew’s solution does not appear to check. Why is that? Please help Andrew to understand this better. Explain your reasoning and correctly factor the original expression, if possible. If the expression is prime, so state.
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-12x^3-28x^2-36x as -4x(3x^2-7x+9) is not right.
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-12x^3-28x^2-36x = -4x(3x^2 + 7x + 9)
-4x * -7x = + 28x, not -28x
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