SOLUTION: Find the product: (3x+0.4)(3x-0.4)

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Question 114200: Find the product: (3x+0.4)(3x-0.4)
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
%283x%2B0.4%29%283x-0.4%29 Start with the given expression

Remember, when you FOIL an expression, you follow this procedure:


Multiply the First terms:%283x%29%2A%283x%29=9x%5E2


Multiply the Outer terms:%283x%29%2A%28-0.4%29=-1.2x


Multiply the Inner terms:%280.4%29%2A%283x%29=1.2x


Multiply the Last terms:%280.4%29%2A%28-0.4%29=-0.16


9x%5E2-1.2x%2B1.2x-0.16 Now collect every term to make a single expression



9x%5E2-0.16 Now combine like terms


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Answer:
So %283x%2B0.4%29%283x-0.4%29 foils and simplifies to 9x%5E2-0.16

In other words, %283x%2B0.4%29%283x-0.4%29=9x%5E2-0.16

Notice how 9x%5E2-0.16 factors back to the original expression %283x%2B0.4%29%283x-0.4%29. So this verifies our answer.