y²-5y=11,y=?
问题描述：
y²-5y=11,y=?
a²-a=64,a=?,a²-1/a²=?
答
y²-5y=11（y-2.5)^2=17.25y-2.5=土√17.25y1=2.5+√17.25 y2=2.5-√17.25a²-a=64,(a-1/2)^2=64.25a-1/2=±√64.25a1=1/2+√64.25 a2=1/2-√64.25a²-1/a²=(a^4-1)/a^2