a=根号17+1分之16=√17-1
(a+1)²=(√17)²
a²+2a-16=0
a5+2a4-17a3-a2+18a-17
=a^5+2a^4-16a^3-a^3-2a²+16a+a²+2a-16-1
=a³(a²+2a-16)-a(a²+2a-16)+(a²+2a-16)-1
=-1
a=根号17+1分之16=√17-1
(a+1)²=(√17)²
a²+2a-16=0
a5+2a4-17a3-a2+18a-17
=a^5+2a^4-16a^3-a^3-2a²+16a+a²+2a-16-1
=a³(a²+2a-16)-a(a²+2a-16)+(a²+2a-16)-1
=-1