SOLUTION: How do I multiply (a-1)(a+3)

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Question 187300: How do I multiply (a-1)(a+3)
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!

%28a-1%29%28a%2B3%29 Start with the given expression.


Now let's FOIL the expression.


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


%28highlight%28a%29-1%29%28highlight%28a%29%2B3%29 Multiply the First terms:%28a%29%2A%28a%29=a%5E2.


%28highlight%28a%29-1%29%28a%2Bhighlight%283%29%29 Multiply the Outer terms:%28a%29%2A%283%29=3%2Aa.


%28a%2Bhighlight%28-1%29%29%28highlight%28a%29%2B3%29 Multiply the Inner terms:%28-1%29%2A%28a%29=-a.


%28a%2Bhighlight%28-1%29%29%28a%2Bhighlight%283%29%29 Multiply the Last terms:%28-1%29%2A%283%29=-3.


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So we have the terms: a%5E2, 3%2Aa, -a, -3


a%5E2%2B3%2Aa-a-3 Now add every term listed above to make a single expression.


a%5E2%2B2%2Aa-3 Now combine like terms.


So %28a-1%29%28a%2B3%29 FOILs to a%5E2%2B2%2Aa-3.


In other words, %28a-1%29%28a%2B3%29=a%5E2%2B2%2Aa-3.