caiyantao
春芽
共回答了16个问题采纳率:87.5% 举报
因为3x²-4x-2=0 所以知X1+X2=-B/A=-(-4)/3=4/3 X1X2=C/A=-2/3
x1²+x2²=X1²+X2²+2X1X2-2X1X2=(X1+X2)²-2X1X2=(4/3)²-2×(-2/3)=28/9
1/x1²+1/x2²=(X1²+X2²)/(X1X2)²------通分
=(28/9)/(-2/3)²=7
x1三次方+x2三次方=(X1+X2)(X1 ²-X1X2+X2 ²)
= (4/3)(28/9-(-2/3))= 136/27
思路是这样的、
1年前
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