初中数学题目，化简求值(2x+3y)²-(2x+y)(2x-y) 求解答步骤 求10道初三分式化简求值求值题+答案
\u521d\u4e00\u6570\u5b66\u3010\u6574\u5f0f\u7684\u52a0\u51cf\u3011\u65b9\u9762\u7684\u9898\uff0c\u6700\u597d\u4eca\u665a7:30\u524d\u7b54\u5b8c\uff0c\u7b54\u6848\u5fc5\u987b\u6b63\u786e\uff0c\u201c\u5316\u7b80\u6c42\u503c\u201d\u9898\u8981\u6b65\u9aa4\uff01\u53ef\u4e0a\u4f20\u7167\u7247\u586b\u7a7a\u9898
1\u3011\u5df2\u77e52x-y=3,\u5219\u4ee3\u6570\u5f0f(y-2x)²-2\uff08-y+2x\uff09+5\u7684\u503c\u4e3a\uff1f
\u7b54\u6848\u4e3a\uff1a(y-2x)²-2\uff08-y+2x\uff09+5=3²- 2*3+5=9-6+5=8
\u9009\u62e9\u9898
1\u3011\u8fd9\u662f\u4e00\u9053\u9009\u62e9\u9898\uff1a\u5982\u679c\u4ee3\u6570\u5f0f4y²-2y+5\u7684\u503c\u4e3a7\uff0c\u90a3\u4e48\u4ee3\u6570\u5f0f2y²-y+1\u7684\u503c\u7b49\u4e8e\uff1f\u9009\u9879\uff1a\u3010A\u30112\u3010B\u30113\u3010C\u3011-2\u3010D\u30114
\u7b54\u6848\u4e3a\uff1a\u75312\uff082y²-y+1\uff09=4y²-2y+2=\uff084y²-2y+5\uff09-3=4\uff0c\u65452y²-y+1=2\uff0c\u9009A
2\u3011\u4e00\u4e2a\u591a\u9879\u5f0f\u51cf\u53bbx²-y²\u7b49\u4e8ex²+y²\uff0c\u8fd9\u4e2a\u591a\u9879\u503c\u662f\uff1f\u9009\u9879\uff1a\u3010A\u30112x²\u3010B\u3011-2x²\u3010C\u30112y²\u3010D\u3011-2y²
\u7b54\u6848\u4e3a\uff1a\uff08x²-y²\uff09+\uff08x²+y²\uff09=2x²\uff0c\u9009A
3\u3011\u4ee3\u6570\u5f0f\uff08xyz²+4xy-1\uff09+\uff08-3xy+xyz²-3\uff09-\uff082xyz²+xy\uff09\u7684\u503c\uff1f\u9009\u9879\uff1a\u3010A\u3011\u4e0ex\uff0cy,\uff0cz\u65e0\u5173\u3010B\u3011\u4e0ex\uff0cy\uff0cz\u7684\u5927\u5c0f\u6709\u5173\u3010C\u3011\u4ec5\u4e0ex\u7684\u5927\u5c0f\u6709\u5173\u3010D\u3011\u4ec5\u4e0ex\uff0cy\u7684\u5927\u5c0f\u6709\u5173
\u7b54\u6848\u4e3a\uff1a\uff08xyz²+4xy-1\uff09+\uff08-3xy+xyz²-3\uff09-\uff082xyz²+xy\uff09=2xyz²-2xyz² +4xy-4xy -4=-4 \u9009A
4\u3011\u4e0b\u5217\u53bb\u62ec\u53f7\u9519\u8bef\u7684\u662f\uff1f\u9009\u9879\uff1a\u3010A\u30112x²-(x-3y)+2x²-x+3y\u3010B\u30111/3x²+(3y²-2xy)=1/3x²-2xy+3y²\u3010C\u3011a²-4(-a+1)=a²-4a-4\u3010D\u3011-(b-2a)-(-a²+b²)= -b+2a+a²-b²
\u7b54\u6848\u4e3a\uff1aC a²-4(-a+1)=a²+4a-4\u624d\u5bf9
\u201c\u5148\u5316\u7b80\uff0c\u5728\u6c42\u503c\u201d \u7684\u9898
1\u3011\u6ce8\u610f\uff1a\u4ec5\u6b64\u9898\u53ea\u5316\u7b80\uff0c\u4e0d\u6c42\u503c\uff1a(3x²-5xy-6y²\uff09-1/2(-y²-4xy+4x²)
\u7b54\u6848\u4e3a\uff1a (3x²-5xy-6y²\uff09-1/2(-y²-4xy+4x²)
\u89e3\uff1a\u539f\u8bd5=3x²-5xy-6y²+1/2y²+2xy-2x²
=3x²-2x²-5xy+2xy-6y²+1/2y²
= x²-3xy-11/2y²
2\u3011\u6c42\u4ee3\u6570\u5f0f5x²-[3x-2(2x-3)+7x²]\u7684\u503c\uff0c\u5176\u4e2dx=1/2
\u5316\u7b80x/2-2[(x-y²/3)-1/6(y²-9/2x)]\uff0c\u5e76\u6c42x= -3\uff0cy= -3/2\u65f6\u7684\u503c
\u89e3\uff1a\uff081\uff095x²-[3x-2(2x-3)+7x²]=5x²-[3x-(4x-6)+7x²]=5x²-\uff083x-4x+6+7x²\uff09=5x²-3x+4x-6-7x²
=-2x²+x-6\uff0c
\u5f53x=1/2\u65f6\uff0c\u539f\u5f0f=-2*\uff081/2\uff09²+1/2 -6=-6
\uff082\uff09x/2-2[(x-y²/3)-1/6(y²-9/2x)]=x/2-2\uff08x-y²/3-1/6y²+1/6\u00d79/2x)=x/2-2\uff08x-y²/2+3/4x)
=x/2-2\uff08-y²/2+7/4x)=x/2+y²-7/2x=-3x+y²
\u5f53x= -3\uff0cy= -3/2\u65f6\uff0c\u539f\u5f0f=-3\u00d7\uff08-3\uff09+\uff08-3/2\uff09²=9+9/4=45/4
3\u3011\u5df2\u77e5\uff0ca\u3001b\u4e92\u4e3a\u76f8\u53cd\u6570\uff0cc\u3001d\u4e92\u4e3a\u5012\u6570\uff0cx=3(a-1)-(a-2b)\uff0cy=c²d+d²-(d/c+c-2)\uff0c\u6c42(2x-y) /3- (3x+2y) /6\u7684\u503c\u3002
\u89e3\uff1a\u7531a\u3001b\u4e92\u4e3a\u76f8\u53cd\u6570\uff0cc\u3001d\u4e92\u4e3a\u5012\u6570\uff0c\u6545a+b=0\uff0ccd=1\uff0c\u6545d=1/c\uff0c
\u6545x=3(a-1)-(a-2b)=3a-3-a+2b=2a+2b-3=2(a-b)-3=-3
y=c²d+d²-(d/c+c-2)=cd*c+d*1/c-d/c-c+2=c+d/c-d/c-c+2=2
\u6545(2x-y) /3- (3x+2y) /6=\uff084x-2y-3x-2y\uff09/6=(x-4y)/6=(-3-4*2)/6=-11/6
. -9(x-2)-y(x-5)
\u5f53x=5,y=12\u65f6,\u6c42\u5f0f\u5b50\u7684\u503c.
2. 5(9+a)\u00d7b-5(5+b)\u00d7a
\u5f53a=5/7\u65f6,\u6c42\u5f0f\u5b50\u7684\u503c.
3. 62g+62(g+b)-b
\u5f53g=5/7,b=16\u65f6,\u6c42\u5f0f\u5b50\u7684\u503c.
4. 3(x+y)-5(4+x)+2y
\u5f53x=9,y=2\u65f6,\u6c42\u5f0f\u5b50\u7684\u503c.
5. (x+y)(x-y)
\u5f53x=0.45,y=0.65\u65f6,\u6c42\u5f0f\u5b50\u7684\u503c.
6. 2ab+a\u00d7a-b
\u5f53a=8.2,b=0.2\u65f6,\u6c42\u5f0f\u5b50\u7684\u503c.
7. 5.6x+4(x+y)-y
\u5f53x=0.25.y=8\u65f6,\u6c42\u5f0f\u5b50\u7684\u503c.
8. 6.4(x+2.9)-y+2(x-y)
\u5f53x=12,y=0.2\u65f6,\u6c42\u5f0f\u5b50\u7684\u503c.
9. (2.5+x)(5.2+y)
\u5f53x=2.3,y=5.1\u65f6,\u6c42\u5f0f\u5b50\u7684\u503c.
10. (2x-3xy+4y)+(x+2xy-3y)
\u5f53x=2.y=3.5\u65f6,\u6c42\u5f0f\u5b50\u7684\u503c.
当然也可以不多次使用平方差公式，直接展开前面一项后后面两项，计算也不是特别复杂
满意请采纳。有其他问题可以追问~
原式=4x²+12xy+9y²-4x²+y²
=12xy+10y²
=2y(6x+5y);
如果本题有什么不明白可以追问，如果满意记得采纳
如果有其他问题请采纳本题后另发点击向我求助，答题不易，请谅解，谢谢。
祝学习进步
(2x+3y)²-(2x+y)(2x-y)
=（2x）²+2x2xx3y+（3y）²-[（2x）²-y²]
=4x²+12xy+9y²-4x²+y²
=10y²+12xy
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绛旓細鍘熷紡 鍗充负 2x²-6x+5-2x²+9x-4-2x²-3x +1=0 -2x²+2 =0 x²=1 x=卤1 甯屾湜鍙互甯埌浣犮丱(鈭鈭)O~
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