解:5x²-8x=-15x²-8x+1=0a=5 b=-8 c=1代入求根公式得x=[8±√(64-20)]/10=(4±√11]/5所以 x1=(4+√11]/5 x1=(4-√11]/5
5x²-8x+1=0x²-8/5x+1/5=0x²-8/5x+(16/25)-(16/25)+1/5=0(x-4/5)²-11/25=0(x-4/5)²=11/25x-4/5=±1/5*根号11x1=4/5+1/5*根号11x2=4/5-1/5*根号11