初中数学完全平方公式
\u521d\u4e2d\u6570\u5b66 \u5b8c\u5168\u5e73\u65b9\u516c\u5f0f \u5e73\u65b9\u5dee\u516c\u5f0f\u8fd0\u7528\u5e73\u65b9\u5dee\u516c\u5f0f\uff0ca\u7684\u5e73\u65b9-b\u7684\u5e73\u65b9\u7b49\u4e8e\uff08a+b)*(a-b)\u7b97\u5b8c\u5f97xy
\u539f\u5f0f=\uff08X²+4X+4\uff09+\uff08Y²-6Y+9\uff09+1
=\uff08X+2\uff09²+\uff08Y-3\uff09²+1
\u2235\u5e73\u65b9\u22650
\u2234\uff08X+2\uff09²+\uff08Y-3\uff09²+1\uff1e0
\u2234\u4e3a\u6b63\u6570
(m-n)^2=m^2-2mn+n^2=3
得：m^2+n^2=5, mn=1
m^4+n^4=(m^2+n^2)^2-2m^2n^2
=25-2
=23
(m+n)^2-(m-n)^2
=4mn=7-3=4
mn=1
(m+n)^2+(m-n)^2=2(m^2+n^2)=10
m^2+n^2=5
m^4+n^4=(m^2+n^2)^2-2m^2n^2
=25-2*1=23
(m+n)^2=m^2+2mn+n^2=7
(m-n)^2=m^2-2mn+n^2=3
→m^2+n^2=5, mn=1
m^4+n^4=(m^2+n^2)^2-2m^2n^2
=25-2 =23
(m+n)^2=m^2+n^2+2mn=7,
(m-n)^2=m^2+n^2-2mn=3,
得出mn=1，m^2+n^2=5
(m^2+n^2)^2=m^4+n^4+2m^2n^2,
m^4+n^4=25-2*1^2=23
(M+N)的平方=7,（m-n)的平方=3
m²+n²+2mn=7①
m²+n²-2mn=3②
①-②得 4mn=4
mn=1
①+②得 2（m²+n²）=10
m²+n²=5
（m²+n²）²=m四次方+n的四次方+2m²n²
25=m四次方+n的四次方+2（mn)²
25=m四次方+n的四次方+2
m四次方+n的四次方=23
他们打字速度也忒回了吧，又比我先做完
(m+n)^2=m^2+n^2+2mn=7 (1)
(m-n)^2=m^2+n^2-2mn=3 (2)
(1)式-(2)式得mn=1
将mn=1代入(1)式得m^2+n^2=5
所以m^4+n^4=(m^2+n^2)^2-2(mn)^2=25-2=23
说明：上述^为次的意思。>_<
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