a-1/a=1 等式左右碰行两边都平方等a平方+1/a平方-2xax1/a=1则a平方+1/a平方=3 等式左锋早右再平方笑基哗a^4+1/a^4=7........a^8+1/a^8=47
a-1/a=1 (a-1/a)^2=a^2+1/a^2-2=1∴a^2+1/a^2=3(清笑漏a^2+1/a^2)升亩^2=a^4+1/答烂a^4+2=9∴a^4+1/a^4=7(a^4+1/a^4)^2=a^8+1/a^8+2=49∴a^8+1/a^8=47