清庭布衣
种子
共回答了18个问题采纳率:100% 举报
1、
x²+(√6+√2)x+2√3=0
a=1,b=√6+√2,c=2√3
所以△=b²-4ac=6+2√12+2-8√3
=6-2√12+2
=(√6-√2)²
所以x=[-(√6+√2)±(√6-√2)]/2
-(√6+√2)-(√6-√2)=-2√6
-(√6+√2)+(√6-√2)=-2√2
所以x1=-√6,x2=-√2
2、
a=mn,b=-(m²+n²),c=mn
所以△=m^4+2m²n²+n^4-4m²n²
=m^4-2m²n²+n^4
=(m²-n²)²
所以=[(m²+n²)±(m²-n²)]/2mn
[(m²+n²)-(m²-n²)]/2mn=2n²/2mn=n/m
[(m²+n²)+(m²-n²)]/2mn=2m²/2mn=m/n
所以x1=n/m,x2=m/n
1年前
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