\(\left(x+1\right)^2=121\\ =>\left(x+1\right)^2=11^2\\ TH1:x+1=11\\ =>x=11-1\\ =>x=10\\ TH2:x+1=-11\\ =>x=-11-1\\ =>x=-12\)
Vậy: ...
TH1: (x + 1)2 = 121
➩(x + 1)2 = 112
➩x + 1 = 11
➩x = 11 - 1
➩x = 10
TH2: (x + 1)2 = 121
➩(x + 1)2 = (-11)2
➩x + 1 = -11
➩x = (-11) - 1
➩x = -12