SOLUTION: 7. (3x + 4y)(3x - 4y)

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Question 171727: 7. (3x + 4y)(3x - 4y)
Found 2 solutions by checkley77, jim_thompson5910:
Answer by checkley77(12844) About Me  (Show Source):
You can put this solution on YOUR website!
(3x + 4y)(3x - 4y)
3x+4y
3x-4y
---------------------
9x^2+12xy-12xy-16y^2
9x^2-16y^2 ans.

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

%283x%2B4y%29%283x-4y%29 Start with the given expression.


Now let's FOIL the expression.


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


%28highlight%283x%29%2B4y%29%28highlight%283x%29-4y%29 Multiply the First terms:%283%2Ax%29%2A%283%2Ax%29=9%2Ax%5E2.


%28highlight%283x%29%2B4y%29%283x%2Bhighlight%28-4y%29%29 Multiply the Outer terms:%283%2Ax%29%2A%28-4%2Ay%29=-12%2Ax%2Ay.


%283x%2Bhighlight%284y%29%29%28highlight%283x%29-4y%29 Multiply the Inner terms:%284%2Ay%29%2A%283%2Ax%29=12%2Ax%2Ay.


%283x%2Bhighlight%284y%29%29%283x%2Bhighlight%28-4y%29%29 Multiply the Last terms:%284%2Ay%29%2A%28-4%2Ay%29=-16%2Ay%5E2.


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9%2Ax%5E2-12%2Ax%2Ay%2B12%2Ax%2Ay-16%2Ay%5E2 Now collect every term to make a single expression.


9%2Ax%5E2-16%2Ay%5E2 Now combine like terms.


So %283x%2B4y%29%283x-4y%29 FOILs to 9%2Ax%5E2-16%2Ay%5E2.


In other words, %283x%2B4y%29%283x-4y%29=9%2Ax%5E2-16%2Ay%5E2.