Question

先化简 再求值(a-2)\(a^2-1)÷【1-（2a-3）\（a-1)】 a=根号2

初中数学化简求值题

Answer 1

解：原式=(a-2)/(a+1)(a-1)÷[(a-1-2a+3)/(a-1)]
=(a-2)/(a-1)(a+1)÷(2-a)/(a-1)
=(a-2)/(a+1)(a-1)x(a-1)/(2-a)
=(a-2)/(a+1)x1/(2-a)
=(a-2)/(a+1)x(-1/(a-2)
=-1/(a+1)
带入得 原式=-根号2+1