roger_cheng
花朵
共回答了19个问题采纳率:89.5% 举报
1,c²=ab-9=(6-b)b-9=-(b-3)^2;
=>c=0,b=3,a=3(平方数非负,c只能为零)
2,不知道证什么,没写清楚
3,x1+x2=2k+1>2 => k>1/2;
x1*x2=k^2+1>1 => k>0;
判别式=(2k+1)^2-4(k^2+1)>=0 => k>=3/4;
所以:k>=3/4
x1/x2=1/2 =>x2=2x1;
=>3x1=2k+1;
2(x1^2)=k^2+1
解得:k=1,或k=7;
1年前
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