선화간, 재평가: 1-[(x)-1/1-x]2를 x2-x+1/x2-2x+1로 나눈 값, 여기서 x2-x+5=0

선화간, 재평가: 1-[(x)-1/1-x]2를 x2-x+1/x2-2x+1로 나눈 값, 여기서 x2-x+5=0

원식=1-[(x)-1/ (1-x)]²ᄉ[(x²-x+1)/(x²-2x+1)]
=1-[x(1-x)/(1-x)-1/(1-x)]²ᄉ[(x²-x+1)/(x-1)²]
=1-[(x-x²-1)/(1-x)]²×[(x-1)²/(x²-x+1)]
=1-[(x²-x+1)/(x-1)]²×[(x-1)²/(x²-x+1)]
=1-[(x²-x+1)²/(x-1)²]×[(x-1)²/(x²-x+1)]
=1-(x²-x+1)
=-(x²-x)
☞ x²-x+5=0
☞ x²-x=-5
원식 = -(-5)
=5