初一数学题 代数式求值 七年级数学代数式求值练习题
\u521d\u4e00\u6570\u5b66\u4ee3\u6570\u5f0f\u6c42\u503c\u98983ab-4ab+8ab-7ab+ab=______\uff0e
4\uff0e7x-(5x-5y)-y=______\uff0e
5\uff0e23a3bc2-15ab2c+8abc-24a3bc2-8abc=______\uff0e
6\uff0e-7x2+6x+13x2-4x-5x2=______\uff0e
7\uff0e2y+(-2y+5)-(3y+2)\uff1d______\uff0e
11\uff0e(2x2-3xy+4y2)+(x2+2xy-3y2)=______\uff0e
12\uff0e2a-(3a-2b+2)+(3a-4b-1)=______\uff0e
13\uff0e-6x2-7x2+15x2-2x2\uff1d______\uff0e
14\uff0e2x-(x+3y)-(-x-y)-(x-y)\uff1d______\uff0e
16\uff0e2x+2y-[3x-2(x-y)]=______\uff0e
17\uff0e5-(1-x)-1-(x-1)=______\uff0e
18\uff0e( )+(4xy+7x2-y2)=10x2-xy\uff0e
19\uff0e(4xy2-2x2y)-( )=x3-2x2y+4xy2+y3\uff0e
21\uff0e\u5df2\u77e5A=x3-2x2+x-4\uff0cB=2x3-5x+3\uff0c\u8ba1\u7b97A+B=______\uff0e
22\uff0e\u5df2\u77e5A=x3-2x2+x-4\uff0cB=2x3-5x+3\uff0c\u8ba1\u7b97A-B=______\uff0e
23\uff0e\u82e5a=-0.2\uff0cb=0.5\uff0c\u4ee3\u6570\u5f0f-(|a2b|-|ab2|)\u7684\u503c\u4e3a______\uff0e
25\uff0e\u4e00\u4e2a\u591a\u9879\u5f0f\u51cf\u53bb3m4-m3-2m+5\u5f97-2m4-3m3-2m2-1\uff0c\u90a3\u4e48\u8fd9\u4e2a\u591a\u9879\u5f0f\u7b49\u4e8e______\uff0e
26\uff0e-(2x2-y2)-[2y2-(x2+2xy)]=______\uff0e
27\uff0e\u82e5-3a3b2\u4e0e5ax-1by+2\u662f\u540c\u7c7b\u9879\uff0c\u5219x=______\uff0cy=______\uff0e
28\uff0e(-y+6+3y4-y3)-(2y2-3y3+y4-7)\uff1d______\uff0e
29\uff0e\u5316\u7b80\u4ee3\u6570\u5f0f4x2-[7x2-5x-3(1-2x+x2)]\u7684\u7ed3\u679c\u662f______\uff0e
30\uff0e2a-b2+c-d3=2a+( )-d3=2a-d3-( )=c-( )\uff0e
31\uff0e3a-(2a-3b)+3(a-2b)-b=______\uff0e
32\uff0e\u5316\u7b80\u4ee3\u6570\u5f0fx-[y-2x-(x+y)]\u7b49\u4e8e______\uff0e
33\uff0e[5a2+( )a-7]+[( )a2-4a+( )]=a2+2a+1\uff0e
34\uff0e3x-[y-(2x+y)]=______\uff0e
35\uff0e\u5316\u7b80|1-x+y|-|x-y|(\u5176\u4e2dx\uff1c0\uff0cy\uff1e0)\u7b49\u4e8e______\uff0e
36\uff0e\u5df2\u77e5x\u2264y\uff0cx+y-|x-y|=______\uff0e
37\uff0e\u5df2\u77e5x\uff1c0\uff0cy\uff1c0\uff0c\u5316\u7b80|x+y|-|5-x-y|=______\uff0e
38\uff0e4a2n-an-(3an-2a2n)\uff1d______\uff0e
39\uff0e\u82e5\u4e00\u4e2a\u591a\u9879\u5f0f\u52a0\u4e0a-3x2y+2x2-3xy-4\u5f97
2x2y+3xy2-x2+2xy\uff0c
\u5219\u8fd9\u4e2a\u591a\u9879\u5f0f\u4e3a______\uff0e
40\uff0e-5xm-xm-(-7xm)+(-3xm)=______\uff0e
41\uff0e\u5f53a=-1\uff0cb=-2\u65f6\uff0c
[a-(b-c)]-[-b-(-c-a)]\uff1d______\uff0e
43\uff0e\u5f53a=-1\uff0cb=1\uff0cc=-1\u65f6\uff0c
-[b-2(-5a)]-(-3b+5c)\uff1d______\uff0e
44\uff0e-2(3x+z)-(-6x)+(-5y+3z)=______\uff0e
45\uff0e-5an-an+1-(-7an+1)+(-3an)\uff1d______\uff0e
46\uff0e3a-(2a-4b-6c)+3(-2c+2b)=______\uff0e
48\uff0e9a2+[7a2-2a-(-a2+3a)]=______\uff0e
50\uff0e\u5f532y-x=5\u65f6\uff0c5(x-2y)2-3(-x+2y)-100=______\uff0e
\u4ee3\u6570\u5f0f\u57fa\u672c\u5185\u5bb9\u7ec3\u4e60\u9898\uff1a(\u7b54\u6848\u90e8\u5206)
1\u3001\u4e0b\u5217\u5f0f\u5b50\u4e2d\u4ee3\u6570\u5f0f\u7684\u4e2a\u6570\u6709 8 \u4e2a\uff0c\u5206\u5f0f\u6709 1 \u4e2a\uff0c\u65e0\u7406\u5f0f\u6709 2 \u4e2a\u3002
5\u3001 ba \u300134 a-2b \u3001S =vt \u30013\u03c0 \u3001m\u30013x-6>5\u3001 -5x2 y z10\u3001a+3a2-1 \u3001x2+1.
2\u3001\u591a\u9879\u5f0f1-x24 \u7684\u6700\u9ad8\u6b21\u9879\u7cfb\u6570\u662f - 14 .
3\u3001\u82e5a+b+c=0,\u5316\u7b80a(1b + 1c )+b(1c + 1a )+ c(1a + 1b )= -3
4\u3001\u5982\u679c\u67092007\u540d\u5b66\u751f\u6392\u6210\u4e00\u5217\uff0c\u63091\u30012\u30013\u30014\u30015\u30014\u30013\u30012\u30011\u30012\u30013\u30014\u30015\u30014\u30013\u30012\u30011\u2026\u2026\u7684\u89c4\u5f8b\u62a5\u6570\uff0c\u90a3\u4e48\u7b2c2007\u540d\u5b66\u751f\u6240\u62a5\u7684\u6570\u662f 3 \uff0e
5\u3001\u4e0b\u5217\u5404\u5f0f\u4e2d\u4e8c\u6b21\u6839\u5f0f\u7684\u4e2a\u6570\u6709 5 \u4e2a.
\u2460-3 \u2461m2+1 \u246227 \u2463-x2-1 \u2464-(-3)3 \u2465a+1 (a<-2) \u2466m2-2m+7 \u2467 16
6\u3001\u51fd\u6570y = 2x+31-x+1 \u7684\u81ea\u53d8\u91cfx\u7684\u53d6\u503c\u8303\u56f4\u662f x\u2265-1\u4e14x\u22600 .
7\u3001\u82e5\u4ee3\u6570\u5f0fx+1x+2 \u00f7 x+3x+4 \u6709\u610f\u4e49\uff0c\u5219x\u7684\u53d6\u503c\u8303\u56f4\u662f x\u2260-2\u4e14x\u2260-3\u4e14x\u2260-4 .
8\u3001\u7ed9\u51fa\u7684\u4e0b\u5217\u8ba1\u7b97\u6216\u5316\u7b80\uff1a\uff081\uff09(a2)4= a6\uff0c\uff082\uff09(-3a)3 =-27 a3
\uff083\uff092-2= 14 \uff0c \uff084\uff09a2 -2a=-3a(a<0)\u5176\u4e2d\u6b63\u786e\u4e2a\u6570\u6709\uff08 C \uff09
A\uff0e1\u4e2a B.2\u4e2a C.3\u4e2a D.4\u4e2a
9\u3001\u5df2\u77e5a\u3001b\u662f\u6b63\u6574\u6570\uff0c\u4e14a + b = 1998 ,\u5219a+b= 1110 .
10\u3001\u5982\u679c\u4e8c\u6b21\u4e09\u9879\u5f0f3x2 \u2013 4x +2k\u5728\u5b9e\u6570\u8303\u56f4\u5185\u603b\u80fd\u5206\u89e3\u6210\u4e24\u4e2a\u4e00\u6b21\u56e0\u5f0f\u7684\u4e58\u79ef\uff0c\u5219k\u7684\u53d6\u503c\u8303\u56f4\u662f k\u2264 23 .
11\u3001\u6570\u5b66\u6e38\u620f\uff1a\u89c4\u5b9a\uff0c\u5bf9\u4efb\u610f\u5b9e\u6570\u5bf9\uff08a\uff0cb\uff09\u6309\u89c4\u5219\u4f1a\u5f97\u5230\u4e00\u4e2a\u65b0\u7684\u5b9e\u6570\uff1aa2+b+1.\u4f8b\u5982\u628a\uff085\uff0c\u20131\uff09\u653e\u5165\u5176\u4e2d\uff0c\u5c31\u4f1a\u5f97\u523052+(\u20131)+1=25.\u73b0\u5c06\u5b9e\u6570\u5bf9(\u20133\uff0c2)\u653e\u5165\u5176\u4e2d\u5f97\u5230\u5b9e\u6570n\uff0c\u518d\u5c06\u5b9e\u6570\u5bf9\uff08n\uff0c\u20131\uff09\u653e\u5165\u5176\u4e2d\u540e\uff0c\u5f97\u5230\u7684\u5b9e\u6570\u662f 144 .
12\u3001\u5df2\u77e5 \uff0c\u5f53n=1\u65f6\uff0ca1=0\uff1b\u5f53n=2\u65f6\uff0ca2=2\uff1b\u5f53n=3\u65f6\uff0c a3=0\uff1b\u2026 \u5219a1+a2+a3+a4+a5+a6\u7684\u503c\u4e3a 6 \uff0e
13\u3001\u5206\u89e3\u56e0\u5f0f\uff1a
\u89e3\uff1a\uff081\uff09ax2 -4ax+4a \uff082\uff09a3 \u2013 a
= a(x2 -4x+4) =a(a2 \u2013 1)
= a (x-2)2 =a(a+1)(a-1)
\uff083\uff092x2+3x-6 \u22352x2+3x-6=0\u7684\u4e24\u6839\u4e3a
=2\uff08x-\u03b1\uff09(x-\u03b2) x= -3+574 \u548cx= -3-574
\u5176\u4e2d\u03b1\u3001\u03b2\u4e3a\u4e00\u5143\u4e8c\u6b21\u65b9\u7a0b \u2234 2x2+3x-6
2x2+3x-6=0\u7684\u4e24\u6839\u3002 = 2\uff08x- -3+574 \uff09(x- -3-574 )
14\u3001\u8ba1\u7b97\uff1a(1+ x2-1 x2-2x+1 )\u00f71x-1
\u89e3\uff1a\u539f\u5f0f=[1+ (x+1)(x-1) (x-1)2 ]\u00d7(x-1)
=(1+ x+1x-1 )\u00d7(x-1)
= 2xx-1 \u00d7(x-1)
= 2x
15\u3001\u5148\u5c06\u5f0f\u5b50\uff081 + 1x \uff09\u00f7x2-1 x2 \u5316\u7b80\uff0c\u7136\u540e\u8bf7\u4f60\u81ea\u9009\u4e00\u4e2a\u7406\u60f3\u7684x\u503c\u6c42\u51fa\u539f\u5f0f\u7684\u503c.
\u89e3\uff1a\uff081 + 1x \uff09\u00f7x2-1 x2 \u5bf9\u4e8ex\u7684\u53d6\u503c\u53ef\u81ea\u5df1\u9009\u53d6\uff0c
= x+1x \u00d7 x2 (x+1)(x-1) \u4f46x\u4e0d\u53ef\u53d60\u30011\u548c-1,\u5426\u5219
= xx-1 \u65e0\u610f\u4e49\u3002
16\u3001\u5df2\u77e5\uff0ca >0\uff0cb|a|>|b|.
\u5316\u7b80\uff1a|a+b| + |a+c| \u2013 |c-b|
\u89e3\uff1a\u2235a >0\uff0cb|a|>|b|
\u2234 a + b > 0 , a + c < 0 ,c \u2013 b < 0
\u2234 |a+b| + |a+c| \u2013 |c-b|
= a+b-(a+c)+(c-b)
= a+b-a-c+c-b
=0
\u8fd9\u53ef\u662f\u6211\u82b1\u94b1\u4e70\u7684\u54e6\uff0c\u8ba4\u771f\u505a\uff0c\u7b54\u6848\u6211\u6253\u4e0a\u4e86\u3002
\u6ee1\u610f\u5417?
代数式在实数范围内,代数式分为有理式和无理式。
1.x=5
2.1/2ah a=0.6
3.c
4.c
5.B
6.A
7.2X2-4X-1/2=6
2-1/2=3/2
6X3/2=9
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