Hanna F.

asked • 11/28/16

(√7a+4 - √3-a)^2

7a+4 is under one root 
3-a is under on root
i get I need to do foil but I don't know how 
the ^2 means its squared

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Inactive Tutor answered • 11/28/16

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You need to square the term that is parenthesis.
 
(√7a+4 - √3-a)(√7a+4 - √3-a)
 
 
Now can you do it?
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Hanna F.

I get all the parts in foil except the part where you have to do -√3-a * √7a+4. 
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11/28/16

Inactive Tutor

You take the product of those square-roots and double the product.
 
√(7a + 4)2 - 2√(21a + 12 - 7a2 - 4a) + √(3 - a)2 
 
 
What I just did was expand the whole thing using FOIL.  Since you understood the FOIL part, you should have arrived at this.
 
The first and last terms undo the radicals and maintain the value that is under that radical.  As a result, you get
 
(7a + 4) + 2√(21a + 12 - 7a2 - 4a) + (3 - a)
 
 
Combine like terms on the first and last terms.
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11/28/16

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