Question

（x减2分之x加2 减x平方减4x加4分之x减4）除以x平方加x 分之x平方减1 其中x=2＋根号2

Answer 1

[(x+2)/(x-2)-(x-4)/(x^2-4x+4)]÷(x^2-1)/(x^2+x)

=[(x^2-4)/(x-2)^2-(x-4)/(x-2)^2]*x(x+1)/(x-1)(x+1)

=(x^2-x)/(x-2)^2*x/(x-1)

=x(x-1)/(x-2)^2*x/(x-1)

=x^2/(x-2)^2

=(2+√2)^2/(√2)^2

=3+2√2