初一数学求值题。线就要。
\u521d\u4e00\u6570\u5b66\u6c42\u503c\u9898\u5c06(a+b)\u770b\u4f5c\u4e00\u4e2a\u6574\u4f53\uff0c\u53ef\u5f97
[(a+b)-1][(a+b)+1]=8
(a+b)²-1²=8
(a+b)²=9
a+b=3 \u6216\u8005 a+b=-3
\u89e3\uff1a
A+B=5x²-mx+n-3y²+2x-1=5x²-3y²+(2-m)x+n-1
\u2235\u4e0d\u542b\u4e00\u6b21\u9879\u548c\u5e38\u6570\u9879
\u22342-m=0,n-1=0
\u2234m=2,n=1
m²-2mn+n²=(m-n)²=1
①+②得5x=2m-1
x=(2m-1)/5
把x=(2m-1)/5代入①得2(2m-1)/5+y=m
4m-2+5y=5m
y=(m+2)/5
所以-(2m-1)/5+5(m+2)/5=4
-2m+1+5m+10=20
3m=9
m=3
(1)+(2)得
5x=2m-1
∴x=(2m-1)/5
把x=(2m-1)/5代入(1)得
2(2m-1)/5+y=m
∴y=(m+2)/5
∵-x+5y=4
∴-(2m-1)/5+(m+2)=4
∴-2m+1+5m+10=20
3m=9
∴m=3
是不是满足-x+5y=4
m=3
要过程吗
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