解方程⑴2x^2-4x+3 √ x^-2x+6=15 ⑵ 3/(x^2-2x-3)=2x^2-4x-

网友回答

(1)2x²-4x+3√(x²-2x+6)=15
2x²-4x+12+3√(x²-2x+6)-27=0
2(x²-2x+6)+3√(x²-2x+6)-27=0
2[√(x²-2x+6)]²+3√(x²-2x+6)-27=0
令√(x²-2x+6)=t,√(x²-2x+6)=√[(x-1)²+5]>0,因此t>0方程变为2t²+3t-27=0
(t-3)(2t+9)=0
t=3或t=-9/2(