6x方-5x-1>0 4x方+4x-15≤0 5x方-2x+3>0 9x方+6x+1>0 3x方-4x+5<0 6x方+5x<4 -x方+5x-5>1
问题描述:
6x方-5x-1>0 4x方+4x-15≤0 5x方-2x+3>0 9x方+6x+1>0 3x方-4x+5<0 6x方+5x<4 -x方+5x-5>1
答
1.6x²-5x-1=(x-1)(6x+1)>0,x>1或x<-1/62.4x²+4x-15=(2x-3)(2x+5)≤0,-2/5≤x≤2/33.9x²+6x+1=(3x+1)²>0,x∈R4.3x²-4x+5<0,因为a=3>0,△=-44<0,所以x∈R5.6x²+5x<4,6x²+...