题目内容
计算:
(1)(
)2-0.25+1+|-5|-(1
)2×
(2)先化简,再求值:(5a2-3b2)+(3b2-4a2)-
(4ab-2).其中a=1,b=1.
(1)(
| 1 |
| 2 |
| 1 |
| 2 |
| 4 |
| 9 |
(2)先化简,再求值:(5a2-3b2)+(3b2-4a2)-
| 1 |
| 2 |
(1)原式=
-
+1+5-
×
=6-1=5;
(2)原式=5a2-3b2+3b2-4a2-2ab+1=a2-2ab+1,
当a=1,b=-1时a2-2ab+1=1-2×1×(-1)+1=4.
| 1 |
| 4 |
| 1 |
| 4 |
| 9 |
| 4 |
| 4 |
| 9 |
(2)原式=5a2-3b2+3b2-4a2-2ab+1=a2-2ab+1,
当a=1,b=-1时a2-2ab+1=1-2×1×(-1)+1=4.
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