题目内容
计算、解方程:
(1)计算:(
-
)(5
-
);
(2)解方程:(x+1)(x+2)=2x+4;
(3)计算:tan30°sin60°+cos230°-sin245°tan45°.
(1)计算:(
| ||
| 2 |
|
|
| 1 | ||
|
(2)解方程:(x+1)(x+2)=2x+4;
(3)计算:tan30°sin60°+cos230°-sin245°tan45°.
(1)原式=(
-
)(
-
)=5-
-
+
;
(2)x2+3x+2=2x+4,
x2+x-2=0,
(x-1)(x+2)=0,
∴x1=1,x2=-2;
(3)原式=
×
+(
)2-(
)2×1,
=
+
-
=
.
| 2 |
| ||
| 5 |
5
| ||
| 2 |
| ||
| 5 |
| ||
| 5 |
| 5 |
| ||
| 5 |
(2)x2+3x+2=2x+4,
x2+x-2=0,
(x-1)(x+2)=0,
∴x1=1,x2=-2;
(3)原式=
| ||
| 3 |
| ||
| 2 |
| ||
| 2 |
| ||
| 2 |
=
| 1 |
| 2 |
| 3 |
| 4 |
| 1 |
| 2 |
=
| 3 |
| 4 |
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