已知实数X,Y满足X2+3X+2Y-3=0,则X+Y的最大值是
人气:464 ℃ 时间:2019-08-20 00:44:11
解答
设k=x+y,y=k-x代入x^2+3x+2y-3=0
x^2+3x+2(k-x)-3=0
x^2+x+2k-3=0
判别式=1-4(2k-3)>=0
1-8k+12>=0
k
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