已知x=2/(3根号2-4),求(x^2-8x+6)/(x-4)的值
问题描述:
已知x=2/(3根号2-4),求(x^2-8x+6)/(x-4)的值
答
已知条件化为x=2/(3√2-4)=2(3√2+4)/(3√2-4)(3√2+4)=2(3√2+4)/2=3√2+4,则(x^2-8x+6)/(x-4)=[(3√2+4)^2-8(3√2+4)+6]/(3√2+4-4)=[18+24√2+16-24√2-32+6]/3√2=8/3√2=4√2/3