Cara menyelesaikan ×2 -4× -12=0​

x² – 4x – 12 = 0

Cara 1 :

x² – 6x + 2x – 12 = 0

x(x – 6) + 2(x – 6) = 0

( x + 2 ) ( x – 6 ) = 0

x = – 2,        x = 6

Cara 2 :

x₁ + x₂ = -b/a = 4

x₁ · x₂ = c/a = – 12

Maka nilai x₁ dan x₂ yg memenuhi persaman diatas

6 + (-2) = 4

6 (-2) = -12

=> x₁ = 6     x₂ = -2