Question

解下列方程：(1)x²=-4x (2)(3x-2)²=9x (3)(x-2)²=2-x

Answer 1

(1)x²=-4x

x²+4x=0

x(x+4)=0

x=0或x=-4

(2)(3x-2)²=9x

9x²-12x+4=9x

9x²-21x+4=0

德尔塔=21²-4*4*9=297

x=(21±3√33)/18=(7±√33)/6

x=(7+√33)/6或x=(7-√33)/6

(3)(x-2)²=2-x

(x-2)²+(x-2)=0

(x-2)(x-2+1)=0

(x-2)(x-1)=0

x=2或x=1