内容正文:
|-9|)÷4=13(
&
).
5
:
LMNE\]R
13̂
_`
.
23.(1)
abcd@AB[
12̂
efgh
.
(2)
iT
N
jk@"[
a.
①lTMmTNno8,a-2+a=12,p+a=7;
②lTMmTNqo8,2-a-a=12,p+a=-5.
,-T
N
jk@"[
-5
'
7.
(3)
labrsncd8
,MN=2-(-5)=7;
labr
sqcd8
,MN=7-2=5.
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M
tT
N
uv@9W[
5
'
7.
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0
、
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1 2 3 4 5 6 7 8 9 10
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A C D D D A D A A D
1
、11.-23,-
8
27; 12.9.08×10
6;
13.4; 14.6; 15.0; 16.q;
17.-3; 18.-19102,(-1)
n+1·
2n-1
n2+2
.
2
、19.(1)m=3,n=4,a=-125;
(2)(-a+m)÷n=[-(-125)+3]÷4=32.
20.(1)0; (2)-219314; (3)-2.
21.(1)<,<,>;
(2)|a+b|-|a+c|+|b-c|=-(a+b)+(a+c)+
(b-c)=-a-b+a+c+b-c=0.
22.(1)(-2)
w
3=(-2)×32+2×(-2)×3+(-2)
=-32;
(2)a+12 w3=
a+1
2 ×3
2+2×a+12 ×3+
a+1
2 =8a
+8.
(8a+8)
w
(-12)=(8a+8)×(-
1
2)
2+2(8a+8)×
(-12)+(8a+8)=2a+2.
VC
(
a+1
2 w3)w(-
1
2)=8,x2a+2=8.
p+
a=3.
23.(1)4,-4;
(2)
yz
t
{|
,
ab
M
sq}z~
2t̂
efgh
,
ab
N
sn}z~
3t̂
efgh
,
①�m��u�9WC10,��2t+3t+10=20.
p+
t=2.
②�m��uP9WC10,��2t+3t-10=20.
p+
t=6.
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2
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6.
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1.C; 2.D; 3.(-a+1b)
2;
4.D; 5.-2; 6.8; 7.C;
8.1; 9.C; 10.4.
11.(1)-14x; (2)0; (3)-14a
2b.
12.D; 13.5x2-6y2+6;
14.A; 15.1.
16.(1)3x2y+4xy; (2)2a2;
(3)x2-6; (4)32a2b-22ab2.
17.A; 18.2.
19.(1)
./
= 32a
2b-2ac-7a2c.
l
a=-1,b=2,c=-2
8
,
./
=13.
(2)
./
=5x2y+2xy-3.
l
x=-12,y=18,./ =-
11
4.
20.2na+bn;
21.(-1)n+1·(3n-1)xn+1yn;
22.D.
23.(1)7.6;
(2)(1.7n+0.8);
(3)
VC�dN�@��C��
,
m��@������
�
0.8cm,
����dN��@�ghC
:1.7×50=85(cm).
24.(1)300x,320(x-1);
(2)
����d�� ¡¢
,
£(¤¥
:
l
x=17
8
,300x=300×17=5100(
!
),320(x-1)=
320×16=5120(
!
).
VC
5100<5120,
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.
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/
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