大家帮我解下这几道数学题 初二的

\u8bf7\u5927\u5bb6\u5e2e\u6211\u5973\u513f\u89e3\u51e0\u9053\u521d\u4e8c\u7684\u6570\u5b66\u9898\u3002\u8bf7\u5927\u5bb6\u5e2e\u89e3\u8be6\u7ec6\u70b9\uff0c\u975e\u5e38\u611f\u8c22\uff01

1\u3001\u6570\u5b57\u89e3\u5bc6\uff1a\u7b2c\u4e00\u4e2a\u6570\u662f3=2+1\uff0c\u7b2c\u4e8c\u4e2a\u6570\u662f5=3+2\uff0c\u7b2c\u4e09\u4e2a\u6570\u662f9=5+4\uff0c\u7b2c\u56db\u4e2a\u6570\u662f17=9+8\uff0c...,\u89c2\u5bdf\u5e76\u731c\u60f3\u7b2c\u516d\u4e2a\u6570\u662f33=17+16\u3002


2\u3001\u6570\u5f62\u7ed3\u5408\u9898\u3002
\u82e6a,b,c\u8868\u793a\u6570\u8f74\u7684\u4e09\u4e2a\u70b9\uff0c\u4e14c\u70b9\u5728a\u3001b\u4e4b\u95f4\uff0c\u8bd5\u8bf4\u660e\uff1a|a-c|+|c-b|=|a-b|
2`\u5982a>c>b|\uff1a|a-c|+|c-b=a-c+c-b=a-b
a-b\u4e3a\u6b63\uff0c|a-b|\uff1da-b
\u5982b>c>a|\uff1a|a-c|+|c-b=c-a+b-c=-a+b
a-b\u4e3a\u8d1f\uff0c|a-b|\uff1d\uff0d\uff08a-b\uff09=-a+b

\u4e00.\uff08\u201c^\u201d\u8fd9\u4e2a\u7b26\u53f7\u662f\u8c01\u662f\u8c01\u7684\u51e0\u6b21\u65b9\uff09
1.\u82e5\u57c3\u514b\u65af\u7684^2-y^2=20\uff0c\u4e14\u57c3\u514b\u65af+y=-5\uff0c\u5219\u57c3\u514b\u65af-y\u7684\u503c\u662f\uff08C\uff09
A.5 B.4 C.-4 D.\u4ee5\u4e0a\u90fd\u4e0d\u5bf9
\u89e3\uff1ax^2-y^2=20\u6240\u4ee5\uff08x+y\uff09\uff08x-y\uff09=20\uff0c\u56e0\u4e3ax+y=-5\u6240\u4ee5\u4ee3\u5165\u5f97x-y=-4
\u9009C -4

2.\u4e0b\u5217\u591a\u9879\u5f0f\u7684\u4e58\u6cd5\u4e2d\uff0c\u53ef\u4ee5\u7528\u5e73\u65b9\u5dee\u516c\u5f0f\u8fdb\u884c\u8ba1\u7b97\u7684\u662f\uff08B\uff09
A.\uff08x+1\uff09\uff081+x\uff09 B.\uff082\u5206\u4e4b1a+b\uff09\uff08b-2\u5206\u4e4b1a\uff09
C.\uff08-a+b\uff09\uff08a-b\uff09 D.\uff08x^2-y\uff09\uff08x+y^2\uff09
2\u5206\u4e4b1a\u4e0eb\u5e73\u65b9\u5dee\uff01

3.\u82e54x^2+kx+4\u5206\u4e4b1 \u662f\u5b8c\u5168\u5e73\u65b9\u516c\u5f0f\uff0c\u5219k\u7684\u503c\u4e3a\uff08C\uff09
A.2 B.-2 C.2\u6216-2 D.1\u6216-1
\u221ak^2-4*4*4\u5206\u4e4b\u4e00=0 \u89e3\u5f97k=2\u6216-2

4.\u5bf9\u4e8e\u4efb\u4f55\u6574\u6570m\uff0c\u591a\u9879\u5f0f\uff084m+5\uff09^2-9\u90fd\u80fd\uff08A\uff09
A.\u88ab8\u6574\u9664 B.\u88abm\u6574\u9664 C.\u88abm-1\u6574\u9664 D.\u88ab2m-1\u6574\u9664
\u5206\u89e3\u56e0\u5f0f\u5f97 \uff084m+5\uff09^2-9=8\uff082m+1\uff09\uff08m+2\uff09

5.\u5728\u7b49\u5f0f\uff08D\uff09^3 \u9664 \u3010\uff08-2xyz\uff09^2 \u00b72x^4y^3z\u3011=y
A.8x^6 y^5 z^3 B.8x^2 y^2 z C.2x^2 y^2 z D.\u6b63\u8d1f2x^2 y^2 z

\u4e8c.\u586b\u7a7a
1.\u5c06\u591a\u9879\u5f0fx^2+4\u52a0\u4e0a\u4e00\u4e2a\u6574\u5f0f\uff0c\u4f7f\u5b83\u6210\u4e3a\u5b8c\u5168\u5e73\u65b9\u516c\u5f0f\uff0c\u8bd5\u5199\u51fa\u6ee1\u8db3\u4e0a\u8ff0\u6761\u4ef6\u7684\u4e09\u4e2a\u6574\u5f0f__4x______,____-4x______,____________.

2.\u8ba1\u7b97\uff08-a-b\uff09\uff08a-b\uff09= b^2-a^2

3.\uff08m+4\uff09\uff08_m-4_)=m^2-16

4.\uff084x+3y\uff09\uff08_4x-3y_\uff09=16x^2-9y^2

5.\u5df2\u77e5\u4e00\u4e2a\u6b63\u65b9\u5f62\u7684\u8fb9\u957f\u4e3aa cm\uff0c\u82e5\u628a\u8fd9\u4e2a\u6b63\u65b9\u5f62\u7684\u8fb9\u957f\u51cf\u5c113 cm\uff0c\u5219\u9762\u79ef\u51cf\u5c11\u4e86__6a-9____

6.\u5df2\u77e5x^2-\uff08m-1\uff09x+4\u662f\u4e00\u4e2a\u5b8c\u5168\u5e73\u65b9\u5f0f\uff0c\u5219m\u7684\u503c\u4e3a__5\u6216-3___

7.\u5df2\u77e5\u957f\u65b9\u5f62\u7684\u957f\u4e3aa+5\uff0c\u9762\u79ef\u662f\uff08a+5\uff09\uff08a+3\uff09\uff0c\u5219\u5b83\u7684\u5468\u957f\u4e3a__4a+16___

8.\u82e5x^2-4y^2=-15\uff0cx+2y=5.\u5219x=_1_y=_2__

9.[(a+b\uff09^2-(a+b)] \u9664 \uff08a+b\uff09= a+b-1

\u4e09.\u8ba1\u7b97\u5199\u8fc7\u7a0b
1.[\uff08-2xy\uff09^3 \u00b7y-x^3\u00b7\uff08-2xy^2)^2\u00b73\u5206\u4e4b1]\u9664[(xy^2)^2\u00b7\uff08-6x)]
\u4e0a\u4e0b\u7ea6\u53bbx^3y^4\u5f974/3+2x^2/9


2.(x-3)(x^2+9)(x+3)
=(x^2-9)(x^2+9)
=x^4-81

3.(2x-y)(y+2x)-(2y+x)(2y-x),\u5176\u4e2dx=1 \u5316\u7b80\u6c42\u503c
=(4x^2-y^2)-(4y^2-x^2)
=5x^2-5y^2
=5(x^2-y^2)
x=1\u4ee3\u5165\u539f\u5f0f\u5f975-y^2

4.\uff081-4y\uff09\uff081+4y\uff09+\uff081+4y\uff09^2\uff0c\u5176\u4e2dy=5\u5206\u4e4b2 \u5316\u7b80\u6c42\u503c
=(1+4y)(1-4y+1+4y)=2(1+4y)
y=5\u5206\u4e4b2\u4ee3\u5165\u5f97\u539f\u5f0f=22

练习：（1）根号下三分之一*根号下108=三分之根号下3*6倍根号3=6
（2）根号0.4*根号3.6=根号0.4*0.6=0.6倍根号0.4
（3）五倍根号45*二分之三倍根号三分之二=二分之十五倍的根号三十
（4）根号30*根号根号2又三分之二*根号0.4=16
（5)二分之三倍的根号20*（-根号15）*（-三分之一倍的根号48）=180

1是6，二是1.2 三是7.5乘以根号30，四是4倍根号2，五是60

对于根号前没有数的，就把根号里面的乘起来开根就行了，有数的先把数乘起来，再按把剩余的根号程起来再想乘就行啦

1. 6
2. 1.2
3. 7.5√30
4. 4√2
5. 60

注：√ 为根号

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