问题
解答题
化简求值: (1)(
(2)
|
答案
(1)原式=
•3x(x+1)-x(x-1) x2-1 x2-1 x
=3x2+3x-x2+x x
=2x+4
当x=2时,
原式=2×2+4=8
(2)原式=
•x-1 (x-2)2
=(x+2)(x-2) (x+1)(x-1) x+2 x2-x-2
当x=3时,
原式=
=3+2 32-3-2
.5 4
化简求值: (1)(
(2)
|
(1)原式=
•3x(x+1)-x(x-1) x2-1 x2-1 x
=3x2+3x-x2+x x
=2x+4
当x=2时,
原式=2×2+4=8
(2)原式=
•x-1 (x-2)2
=(x+2)(x-2) (x+1)(x-1) x+2 x2-x-2
当x=3时,
原式=
=3+2 32-3-2
.5 4