解题思路:(1)先把分母有理化,再进一步合并化简即可;
(2)先化简代数式,再进一步代入求得数值即可.
(1)原式=
2-1+
3-
2+
4-
3+…+
100-
99
=-1+10
=9;
(2)原式=
(x+3)(x−2)
x•
x(x−2)
x+3-
x2−4x+4−2(x−2)
x2−4x+x2−4x
4
=x2-4x+4-
x2−4x+2−(x−2)
x2−4x
2
=
x2−4x+6+(x−2)
x2−4x
2;
∵
x=
a+
1
a
∴x=a+2+
1
a
∴原式=
1
2[(a+
1
a)2+2+(a+
1
a)(a-
1
a)]=a2+2;
点评:
本题考点: 二次根式的化简求值.
考点点评: 此题考查了分式的化简求值,熟练掌握运算法则是解本题的关键.