题目

化简求值：已知x= ，求代数式 ﹣ 的值． 答案：解：x= 12+1 = 2 ﹣1， 则 2x ﹣ x2−1x2+x = 2(x+1)−x2+1x(x+1) = (x+1)(3−x)x(x+1) = 3−xx = 3−2+12−1 = (4−2)(2+1)(2)2−1 =3 2 +2．

查看本题答案和解析