问题
解答题
计算或解方程: (1)
(2)2cos60°+2sin30°+4tan45°; (3)(x-1)2=2(x-1); (4)x2+3=2(x+2); (5)(tan21°-tan69°+sin^33°+cos^33°)-
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答案
(1)原式=
-4×2
-13
-2 2
+1+23
=2
+1-23
-2
+1+23
=2;2
(2)原式=2×
+2×1 2
+4×1=6;1 2
(3)∵(x-1)2=2(x-1),
∴(x-1)(x-1-2)=0,
∴x1=1,x2=3;
(4)∵x2+3=2(x+2),
∴x2-2x+1=2,
∴(x-1)2=±
,2
∴x1=1+
,x2=1-2
;2
(5)原式=(1+1)×tan6°×
=2.1 tan6°