6. 求下列不等式的解集(1)−x2+5x−6>0-x^{2}+5x-6>0−x2+5x−6>0;(2)2x2−3x+1>02x^{2}-3x+1>02x2−3x+1>0;(3)x2−x+1>0x^{2}-x+1>0x2−x+1>0.