题目内容
(1)解方程:2x2-5x-7=0;
(2)计算:6tan30°+(3.6-π)°-
+(
)-1.
(2)计算:6tan30°+(3.6-π)°-
12 |
1 |
2 |
分析:(1)根据一元二次方程的求根公式,可得答案;
(2)根据先算乘方,再算加减,可得答案.
(2)根据先算乘方,再算加减,可得答案.
解答:解(1)2x2-5x-7=0,
a=2,b=-5,c=-7,
x=
x=-1或x=
;
(2)原式=6×
+1-2
+2
=2
+1-2
+2
=3.
a=2,b=-5,c=-7,
x=
5±
| ||
2×2 |
x=-1或x=
7 |
2 |
(2)原式=6×
| ||
3 |
3 |
=2
3 |
3 |
=3.
点评:本题考查了实数的运算,先算乘方开方,再算加减.
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