问题 解答题
(1)化简:
75
×
6
3
÷
1
2
;   
(2)
4
4-
11
-
4
11
-
7
-
2
3+
7

(3)解方程:(x-1)(x+3)=5;     
(4)x2-4x-12=0(用求根公式).
答案

(1)

75
×
6
3
÷
1
2

=5

3
×
6
3
×
2

=10;   

(2)

4
4-
11
-
4
11
-
7
-
2
3+
7

=

4(4+
11
)
5
-
4(
11
+
7
)
4
-
2(3-
7
)
2

=

16
5
+
4
11
5
-
11
-
7
-3+
7

=

1
5
-
9
11
5

(3)(x-1)(x+3)=5,

x2+2x-3=5,

x2+2x-8=0,

(x+4)(x-2)=0,

 x+4=0或x-2=0,

x1=-4,x2=2;

(4)x2-4x-12=0,

∵a=1,b=-4,c=-12,

b2-4ac=16-4×1×(-12)=64>0,

∴x=

64
2
=
4±8
2

∴x1=6,x2=-2

单项选择题
单项选择题