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> (1)3sin60°+2-1-2cos45°-(2-1)0(2)2x2+6=7x(用配方法解)-数学
(1)3sin60°+2-1-2cos45°-(2-1)0(2)2x2+6=7x(用配方法解)-数学
题目简介
(1)3sin60°+2-1-2cos45°-(2-1)0(2)2x2+6=7x(用配方法解)-数学
题目详情
(1)
3
sin60°+
2
-1
-
2
cos45°-(
2
-1
)
0
(2)2x
2
+6=7x(用配方法解)
题型:解答题
难度:中档
来源:不详
答案
(1)原式=
3
×
3
2
+
class="stub"1
2
-
2
×
2
2
-1
=
class="stub"3
2
+
class="stub"1
2
-1-1
=0.
(2)移项得:2x2-7x=-6,
x2-
class="stub"7
2
x=-3,
配方得:x2-
class="stub"7
2
x+(
class="stub"7
4
)2=-3+(
class="stub"7
4
)2,
(x-
class="stub"7
4
)2=
class="stub"1
16
,
开方得:x-
class="stub"7
4
=±
class="stub"1
4
,
解得:x1=2,x2=
class="stub"3
2
.
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题目简介
(1)3sin60°+2-1-2cos45°-(2-1)0(2)2x2+6=7x(用配方法解)-数学
题目详情
(2)2x2+6=7x(用配方法解)
答案
=
=0.
(2)移项得:2x2-7x=-6,
x2-
配方得:x2-
(x-
开方得:x-
解得:x1=2,x2=