(3√2-√3)²=(3√2)²-2.3.√2.√3 + (√3)²=18-6√6+3=21-6√6
(16-c)/(√c - 4)=(16-c)(√c+4)/(√c-4)(√c+4)=(16-c)(√c+4)/(c-16)=
=-(√c+4)=-√c-4
(3√2-√3)²=(3√2)²-2.3.√2.√3 + (√3)²=18-6√6+3=21-6√6
(16-c)/(√c - 4)=(16-c)(√c+4)/(√c-4)(√c+4)=(16-c)(√c+4)/(c-16)=
=-(√c+4)=-√c-4