问题
解答题
计算: (1)(-2)2×
(2)已知x=
(3)2sin30°+cos60°-tan60°-tan30°+cos245°. |
答案
(1)原式=4×2
-163
+12+8(2+3
)=83
-163
+12+16+83
=28;3
(2)∵x=
<1,1 3
∴原式=
-(x-1)2 x(x-1)
=(x-1)2 x-1
-(x-1)=-1-x x(x-1)
-x+1=-1 x
-3
+1=-1 3
+1-3
=-3 3
+1;4 3 3
(3)原式=2×
+1 2
-1 2
×3
+(3 3
)2=1.2 2