由题意可得a²-a-1=0
a²=a+1
a⁴=（a²）²=（a+1）²=a²+2a+1=a+1+2a+1=3a+2
a³=a•a²=a（a+1）=a²+a=a+1+a=2a+1

2a4−3a2x+2

a3+2a2x−a

=-

93

112

6a+4−3a2x+2

2a+1+2a2x−a

=-

93

112

672a+672-336xa²=-93a-93-186xa²
150xa²=765a+765=765（a+1）=765a²
150x=765
x=5.1．