5. 解关于xxx的不等式. (1)2x2−x−6>02x^{2}-x-6>02x2−x−6>0; (2)−2x2+x+3⩾0-2x^{2}+x+3\geqslant 0−2x2+x+3⩾0; (3)x2−3x−2<0x^{2}-3x-2<0x2−3x−2<0.