(1)x=4 or x=-1/2
(2)x=-23 or x=18
(3)x=8 or x=-9过程...(1)2x² - 4 = 7x 2x² - 7x -4=0(2x+1)(x-4)=0x=4 or x=-1/2(2)x（x+4)=621 x² +4x-621=0(x+23)(x-18)=0x=-23 or x=18(3)(x - 1)(x+2) =70x²+x-2-70=0x²+x-72=0(x-8)(x+9)=0x=8 or x=-9