已知X1,X2是方程3x²+2x-7=0的两实数根,试求下列各式的值:(1)X1²+X2² (2)X2/X1 +X1/X2
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![已知X1,X2是方程3x²+2x-7=0的两实数根,试求下列各式的值:(1)X1²+X2² (2)X2/X1 +X1/X2](/uploads/image/z/2082629-29-9.jpg?t=%E5%B7%B2%E7%9F%A5X1%2CX2%E6%98%AF%E6%96%B9%E7%A8%8B3x%26%23178%3B%2B2x-7%3D0%E7%9A%84%E4%B8%A4%E5%AE%9E%E6%95%B0%E6%A0%B9%2C%E8%AF%95%E6%B1%82%E4%B8%8B%E5%88%97%E5%90%84%E5%BC%8F%E7%9A%84%E5%80%BC%EF%BC%9A%EF%BC%881%EF%BC%89X1%26%23178%3B%2BX2%26%23178%3B+%EF%BC%882%EF%BC%89X2%2FX1+%2BX1%2FX2)
已知X1,X2是方程3x²+2x-7=0的两实数根,试求下列各式的值:(1)X1²+X2² (2)X2/X1 +X1/X2
已知X1,X2是方程3x²+2x-7=0的两实数根,试求下列各式的值:
(1)X1²+X2² (2)X2/X1 +X1/X2
已知X1,X2是方程3x²+2x-7=0的两实数根,试求下列各式的值:(1)X1²+X2² (2)X2/X1 +X1/X2
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
X1²+X2²
=(X1+X2)²-2X1X2
=(-2/3)²-2×(-7/3)
=4/9+14/3
=46/9
X2/X1 +X1/X2
=(X1²+X2²)/(X1X2)
=(46/9)/(-7/3)
=-46/21