已知x+1/x=4,求(1)x2+1/x2的值,(2)x4+1/x4的值
问题描述:
已知x+1/x=4,求(1)x2+1/x2的值,(2)x4+1/x4的值
x的后面是次方
答
x+1/x=4,(1)x2+1/x2=(x+1/x)^2-2 =4^2-2=14(2)x4+1/x4=(x2+1/x2)^2-2 =14^2-2 =194