X1,X2是方程3x²+2x-7=0的两实数根
∴x1+x2=-2/3,x1x2=-7/3
（1）X1²+X2²
=x1²+2x1x2+x2²-2x1x2
=(x1+x2)²-2x1x2
=4/9+14/3
=46/9
（2）X2/X1 +X1/X2
=(x2²+x1²)/(x1x2)
=(46/9)÷(-7/3)
=-46/21