①X² - √2X-1/4=0
x=[√2±√(2+1)]/2
x=(√2±√3)/2
② X(X-4)=2-8x
x²-4x=2-8x
x²+4x-2=0
x=[-4±√(4²+8)]/2
x=-2±√6
③X²-2 √5X+10=0
△=20-40
①X² - √2X-1/4=0
x=[√2±√(2+1)]/2
x=(√2±√3)/2
② X(X-4)=2-8x
x²-4x=2-8x
x²+4x-2=0
x=[-4±√(4²+8)]/2
x=-2±√6
③X²-2 √5X+10=0
△=20-40