Question

已知x加x分之1等于根号5减1,求x的平方加x的平方分之1的值

Answer 1

x + 1/x = √5 - 1

x^2 + 1/x^2 = (x + 1/x)^2 -2 =(√5 -1)^2 - 2 = 4-2√5