Question

(3+√2)²-12 supra √2 =

Answer 1

(3+√2)²-12supra√2=
3+√4-12supra√2=
√7-12supra√2=
-√5supra√2

Answer 2

$(3+ \sqrt{2})^{2} - \frac{12}{ \sqrt{2} }$
  $3^{2} +2*3* \sqrt{2}+ \sqrt{2}^{2} - \frac{12}{ \sqrt{2} }$
   $9+2*3* \sqrt{2}+2- \frac{12}{ \sqrt{2}}$
  $11+6* \sqrt{2} - \frac{12}{ \sqrt{2} }= \\ 11+6\sqrt{2} - \frac{12* \sqrt{2} }{2}$ (am rationalizat cu √2)
  $11+ 6\sqrt{2} -6\sqrt{2}= 11 +0=11$