Question

化简:(2x2一; 3x)-4(x-x2 )

化简求值:
(x-4)/(x^2-1) ÷ (x^2-3x-4)/(x^2+2x+1) +1/(x-1),其中x=2倍根号3+1

Answer 1

(x-4)/(x^2-1) ÷ (x^2-3x-4)/(x^2+2x+1) +1/(x-1)
=2/(x-1),
将x=2倍根号3+1 代入有
(x-4)/(x^2-1) ÷ (x^2-3x-4)/(x^2+2x+1) +1/(x-1)
=(根号3)/3