Question

(3x-1)^2-6x=? Repede

Answer 1

Salutare!

(3x - 1)² - 6x = 0

(3x - 1)² = (3x)² - 2 · 3x · 1 + 1²

            = 9x² - 6x + 1

9x² - 6x + 1 - 6x = 0

9x² - 12x + 1 = 0

a = 9  ;  b = -12  ;  c = 1

Δ = b² - 4ac = (-12)² - 4 · 9 · 1 = 144 - 36 = 108 = 6√3

x₁,₂ = ( -b ± √Δ ) / 2a

x₁ = ( 12 + 6√3 ) / 18 = [ 6 (2 + √3 )]/18 = (2 + √3)/3

x₂ = ( 12 - 6√3 ) / 18 = [ 6 (2 - √3 )]/18 = (2 - √3)/3

S = { (2 - √3)/3 ; (2 + √3)/3 }

Answer 2

(3x-1)²-6x=

=(3x)²-2×3x+1-6x=

=9x²-6x+1-6x=9x²-12x+1