Question

Daca A={ x ∈ Z | $(x-6)^{2}$ = 25 } , atunci A = {........} .

Answer 1

( x - 6 )  - 25 = 0 
( x - 6 - 5 ) · ( x - 6 + 5 ) = 0 
( x -11 ) · ( x -1) = 0 
x -11 = 0  ; x =11 
x - 1 =0   ; x =1 
A = { 1 , 11 }