题:已知x²-7x+2=0.求x²＋1／x²的值

题:已知x²-7x+2=0.求x²＋1／x²的值
题:已知x²-7x+2=0.求x²＋1／x²的值

题:已知x²-7x+2=0.求x²＋1／x²的值
由原方程得：x^2=7x-2 x=(7+41^1/2)/2或x=（7-41^1/2)/2 X^2+1/x^2=7x-2+1/(7x-2)代入得原式=(225+21*42^1/2)/8或原式=（225-21*41^1/2）/8