Question 327308
(3- 2square root7)(3+ 2square root 7)
This is similar to (a - b)*(a + b) = a^2 - b^2
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{{{(3- 2sqrt(7))(3+ 2sqrt(7))}}}
= {{{3^2 - (2sqrt(7))^2}}}
= 9 - 4*7
= -19