(x+y)(x-y)-(x-y)²的计算过程？ 初一数学题！已知（x＋ y）²=9，（x－y）&#...
\u82e5\uff08x+y\uff09²=7\uff0c\uff08x-y\uff09²=4\uff0c\u6c42xy\u548cx²+y²\u7684\u503c\uff08\u5199\u8fc7\u7a0b\uff09\u521d\u770b\u6b64\u9898,\u4fbf\u53ef\u77e5\u7834\u9898\u70b9\u5728"xy"
\u53c8\u77e5(x+y)^2=x^2+y^2+2xy\uff0c\u4e14(x-y)^2=x^2+y^2-2xy
\u5219\u4e24\u5f0f\u76f8\u51cf\uff0c\u53ef\u5f974xy=3\uff0c\u5373xy=3/4
\u53c8\u5c06\u5176\u5e26\u5165\u7b2c\u4e00\u4e2a\u5f0f\u5b50\uff0c\u53ef\u5f97x^2+y^2=7-3/2=5.5
\u6216\u5e26\u5165\u7b2c\u4e8c\u4e2a\u5f0f\u5b50\uff0c\u53ef\u5f97x^2+y^2=4+2x3/4=5.5
\uff08x\uff0b y\uff09²=9
\u6240\u4ee5\uff1ax²+2xy+y²=9\u2026\u2026\u2026\u2026\u2026\u2026\u2460
\uff08x-y\uff09²=4
\u6240\u4ee5\uff1ax²-2xy+y²=4\u2026\u2026\u2026\u2026\u2026\u2026\u2461
\uff08\u2460 + \u2461\uff09\u00f72\u5f97
x²+y²=6.5\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2462
\u628a\u2462\u4ee3\u5165\u2460\uff0c\u5f97
2xy+6.5=9
\u89e3\u5f97\uff1axy = 1.25
(x+y)(x-y)-(x-y)²
=x²-y²-x²+2xy-y²
=2xy-2y²
=2y(x-y)
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分开算就是x的平方减去y的平方 减去x的平方加上2xy 再减去y的平方 最后就剩2xy
要好好学习 没有理由的
所有的题我都可以给你做 但是你将来会后悔
=x²-y²-（x²-2xy+y²）
=x²-y²-x²+2xy-y²
=2xy-2y²
=2y（x-y）
x＝-1
(x-y)((x＋y)-(x-y))
(x-y)*2y
2xy-2y²
绛旓細x+y=y+x x-y=-(y-x)xy=(-x)(-y)x(-y)=-xy x(a+b)=ax+bx x(a-b)=ax-bx (x-y)²=(y-x)²(x-y)³=-(y-x)³...
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绛旓細瀹屽叏骞虫柟鍏紡
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绛旓細浣犲ソ锛(x+y)(x-y)=x^2-y^2
绛旓細=(x-y)³脳(x-y)²脳(x-y)=(x-y)鐨6娆℃柟 (x-y)脳(x-y)鐨4娆℃柟脳(y-x)鐨4娆℃柟 =(x-y)脳(x-y)鐨4娆℃柟脳(x-y)鐨4娆℃柟 =(x-y)鐨9娆℃柟 锛坸-y锛脳锛坹-x锛³脳锛坹-x锛夌殑4娆℃柟 =(x-y)脳銆-(x-y)³]脳(x-y)鐨4娆℃柟 =-(x-y)鐨8娆℃柟 ...
绛旓細鍥犲紡鍒嗚В锛歺(x锛峺)锛峺(y锛峹)=x(x锛峺)+y(x锛峺)=锛坸+y锛(x锛峺)璁＄畻锛歺(x锛峺)锛峺(y锛峹)=x(x锛峺)+y(x锛峺)=锛坸+y锛(x锛峺)=x骞虫柟-y骞虫柟
绛旓細锛坸+y锛夛紙x-y锛=x(x-y)+y(x-y)=x²-xy+xy-y²=x²-y²甯屾湜鍙互甯埌浣 绁濆涔犲揩涔愶紒O(鈭鈭)O~
绛旓細(x+y)(x-y)=XX-XY+YX-YY=X²-Y²銆
