SOLUTION: I forget the formula that applies to this problem (3a-1)^2 Do I multiple 3*2=9would I write the problem as 9a^2 +1?

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Question 253109: I forget the formula that applies to this problem (3a-1)^2 Do I multiple 3*2=9would I write the problem as 9a^2 +1?
Found 2 solutions by palanisamy, jim_thompson5910:
Answer by palanisamy(496) About Me  (Show Source):
You can put this solution on YOUR website!
You have to apply the formula, (a-b)^2 = a^2+b^2-2ab
(3a-1)^2 = (3a)^2+(1)^1-2(3a)*1
=9a^2+1-6a

Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!

%283a-1%29%5E2 Start with the given expression.


%283a-1%29%283a-1%29 Expand. Remember something like x%5E2=x%2Ax.


Now let's FOIL the expression.


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


%28highlight%283a%29-1%29%28highlight%283a%29-1%29 Multiply the First terms:%283a%29%2A%283a%29=9a%5E2.


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


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


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


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So we have the terms: 9a%5E2, -3a, -3a, 1


9a%5E2-3a-3a%2B1 Now add every term listed above to make a single expression.


9a%5E2-6a%2B1 Now combine like terms.


So %283a-1%29%5E2 FOILs to 9a%5E2-6a%2B1.


In other words, %283a-1%29%5E2=9a%5E2-6a%2B1.