Persamaan kuadrat x^2-2x-1=0 mempunyai akar akar x1-2 dan x2-2 adalah

Pers. Kuadrat

• x1+x2 = -2
• x1.x2 = -1
...
Misal :
p → (x1-2)+(x2-2)
p = x1+x2-4
p = -2-4
p = -6

q → (x1-2).(x2-2)
q = x1.x2 - 2x1 - 2x2 + 4
q = x1.x2 - 2(x1+x2) + 4
q = (-1) - 2(-2) + 4
q = 7

Maka, PK barunya :
x² - px + q = 0
x² + 6x +7 = 0