题目内容
先化简,再求值:
(1)(a+1)2-(1-a)(-a-1),其中a=
;
(2)(x-1)(x-2)+x(2x+3)-2,其中x=
.
(1)(a+1)2-(1-a)(-a-1),其中a=
| 3 |
| 4 |
(2)(x-1)(x-2)+x(2x+3)-2,其中x=
| 1 |
| 3 |
(1)原式=a2+2a+1-(a2-1)
=a2+2a+1-a2+1
=2a+2,
当a=
时,原式=2×
+2=
;
(2)原式=x2-2x-x+2+2x2+3x-2
=3x2,
当x=
时,原式=3×(
)2=
.
=a2+2a+1-a2+1
=2a+2,
当a=
| 3 |
| 4 |
| 3 |
| 4 |
| 7 |
| 2 |
(2)原式=x2-2x-x+2+2x2+3x-2
=3x2,
当x=
| 1 |
| 3 |
| 1 |
| 3 |
| 1 |
| 3 |
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