(x√7 - 3√8 ) (x√7 - 3√8 )
To solve this question you must FOIL (First, Outside, Inside, Last) like so
First:
(x√7 - 3√8 ) (x√7 - 3√8 )
x√7 * x√7
For this you will multiply the numbers/variables on the out side together and separately multiply the values inside the square root together
(x*x)(√7*7)
x²√49
7x²
Outside:
(x√7 - 3√8 ) (x√7 - 3√8 )
x√7 * -3√8
(-3*x)(√7*8)
-3x√56
√56 can be further simplified to: 2√14
Now we have: -3x2√14 ---> -6x√14
Inside:
(x√7 - 3√8 ) (x√7 - 3√8 )
The process is the exact same as in the "outside"
x√7 * -3√8
(-3*x)(√7*8)
-3x√56
√56 can be further simplified to: 2√14
Now we have: -3x2√14 ---> -6x√14
Last:
(x√7 - 3√8 ) (x√7 - 3√8 )
-3√8 * -3√8
(-3*-3)(√8*√8)
9√64
9*8
72
Now combine all the products of the FOIL together like so...
7x² - 6x√14 - 6x√14 + 72
Combine like terms:
7x² - 6x√14 - 6x√14 + 72
^^^When you add together square roots the number inside the radical stays the same, and you combine the numbers/variables attached to the radical on the outside
You selected the correct answer:
7x² -12x√14 + 72
Hope this helped!
~Just a girl in love with Shawn Mendes