$color#FF6800 x ^ color#FF6800 2 color#FF6800 - color#FF6800 2 color#FF6800 x color#FF6800 - color#FF6800 1 = color#FF6800 0 $Bạn vẫn xem: Giải phương trình x 2 x 1 0$ $ Hãy thay đổi biến thay đổi vế trái của phương trình bậc nhì thành dạng bình phương của một hiệu hoặc một tổng $ $$left ( color#FF6800 x color#FF6800 - color#FF6800 1
ight ) ^ color#FF6800 2 color#FF6800 - color#FF6800 1 color#FF6800 - color#FF6800 1 ^ color#FF6800 2 = color#FF6800 0 $$left ( x - 1
ight ) ^ 2 color#FF6800 - color#FF6800 1 color#FF6800 - color#FF6800 1 ^ color#FF6800 2 = 0$$left ( x - 1
ight ) ^ 2 = color#FF6800 1 color#FF6800 + color#FF6800 1 ^ color#FF6800 2 $$left ( color#FF6800 x color#FF6800 - color#FF6800 1
ight ) ^ color#FF6800 2 = color#FF6800 2 $$color#FF6800 x color#FF6800 - color#FF6800 1 = pm sqrt color#FF6800 2 $$color#FF6800 x color#FF6800 - color#FF6800 1 = pm sqrt color#FF6800 2 $$color#FF6800 x = pm sqrt color#FF6800 2 color#FF6800 + color#FF6800 1 $$color#FF6800 x = pm sqrt color#FF6800 2 color#FF6800 + color#FF6800 1 $$eginarray l color#FF6800 x = color#FF6800 1 color#FF6800 + sqrt color#FF6800 2 \ color#FF6800 x = color#FF6800 1 color#FF6800 - sqrt color#FF6800 2 endarray$$x = dfrac color#FF6800 - left ( color#FF6800 - 2
ight ) pm sqrt left ( - 2
ight ) ^ 2 - 4 imes 1 imes left ( - 1
ight ) 2 imes 1 $$x = dfrac 2 pm sqrt left ( - 2
ight ) ^ 2 - 4 imes 1 imes left ( - 1
ight ) 2 imes 1 $$x = dfrac 2 pm sqrt left ( color#FF6800 - color#FF6800 2
ight ) ^ color#FF6800 2 - 4 imes 1 imes left ( - 1
ight ) 2 imes 1 $$color#FF6800 x = color#FF6800 dfrac 2 pm sqrt 2 ^ 2 - 4 imes 1 imes left ( - 1
ight ) 2 imes 1 $$eginarray l color#FF6800 x = color#FF6800 dfrac 2 + 2 sqrt 2 2 \ color#FF6800 x = color#FF6800 dfrac 2 - 2 sqrt 2 2 endarray$$eginarray l x = color#FF6800 dfrac 2 + 2 sqrt 2 2 \ x = dfrac 2 - 2 sqrt 2 2 endarray$$eginarray l x = color#FF6800 dfrac 1 + sqrt 2 1 \ x = dfrac 2 - 2 sqrt 2 2 endarray$$eginarray l x = dfrac 1 + sqrt 2 color#FF6800 1 \ x = dfrac 2 - 2 sqrt 2 2 endarray$$eginarray l x = color#FF6800 1 color#FF6800 + sqrt color#FF6800 2 \ x = dfrac 2 - 2 sqrt 2 2 endarray$$eginarray l x = 1 + sqrt 2 \ x = color#FF6800 dfrac 2 - 2 sqrt 2 2 endarray$$eginarray l x = 1 + sqrt 2 \ x = color#FF6800 dfrac 1 - sqrt 2 1 endarray$$eginarray l x = 1 + sqrt 2 \ x = dfrac 1 - sqrt 2 color#FF6800 1 endarray$$eginarray l x = 1 + sqrt 2 \ x = color#FF6800 1 color#FF6800 - sqrt color#FF6800 2 endarray$$color#FF6800 x ^ color#FF6800 2 color#FF6800 - color#FF6800 2 color#FF6800 x color#FF6800 - color#FF6800 1 = color#FF6800 0 $$color#FF6800 D = left ( color#FF6800 - color#FF6800 2
ight ) ^ color#FF6800 2 color#FF6800 - color#FF6800 4 color#FF6800 imes color#FF6800 1 color#FF6800 imes left ( color#FF6800 - color#FF6800 1
ight )$$D = left ( color#FF6800 - color#FF6800 2
ight ) ^ color#FF6800 2 - 4 imes 1 imes left ( - 1
ight )$$D = 4 color#FF6800 - color#FF6800 4 color#FF6800 imes left ( color#FF6800 - color#FF6800 1
ight )$$color#FF6800 x ^ color#FF6800 2 color#FF6800 - color#FF6800 2 color#FF6800 x color#FF6800 - color#FF6800 1 = color#FF6800 0 $$ $ Nếu hotline hai nghiệm của phương trình bậc hai $ ax^2+bx+c=0 $ là $ alpha, eta $ thì ta gồm $ alpha + eta =-dfracba $ , $ alpha imeseta=dfracca$$color#FF6800 alpha color#FF6800 + color#FF6800 eta = color#FF6800 - color#FF6800 dfrac - 2 1 , color#FF6800 alpha color#FF6800 eta = color#FF6800 dfrac - 1 1 $$alpha + eta = color#FF6800 - color#FF6800 dfrac - 2 1 , alpha eta = dfrac - 1 1 $