Question

решите пожалуйста 5-а² при а=1+√2

Answer 1

$a=1+ sqrt{2} \ 5- a^{2} =5- (1+ sqrt{2}) ^{2} = 5-(1^2+2*1* sqrt{2}+ (sqrt{2})^2 )= \ =5- (1+ sqrt{2}) ^{2} = 5-(1+2 sqrt{2}+ 2 )=5- 1+ sqrt{2} = \ =5-1-2 sqrt{2}- 2=2-2 sqrt{2}$