x⁴-x²+6x-8=1x⁴-x²+6x-9=0x⁴-(x-3)²=0(x²+x-3)(x²-x+3)=0∵x²-x+3=x²-x+(1/2)²+3-1/4=(x-1/2)²+11/4≠0∴x²+x-3=0x²+x+(1/2)²-3-1/...