Jika x1dan x2 adalah akar- akar persamaan 2x 2 -3x -1=0, persamaan kuadrat baru yang akar- akarnya (x1– 3) dan (x2 -3) adalah

x1 + x2 = -b/a = -(-3)/2 = 3/2
x1 . x2 = c/a = -1/2
persamaan baru
x² - (x1 - 3 + x2 - 3)x + (x1-3)(x2-3) = 0
x² - (x1+x2-6)x + (x1.x2-3x1-3x2+9) = 0
x² - (3/2 - 6)x + ((-1/2) - 3(x1+x2) + 9) = 0
x² - (3/2-12/2)x + ((-1/2)-3(3/2)+9) = 0
x² - (-9/2)x + ((-1/2)-9/2+18/2) = 0
x² + (9/2)x + (8/2) = 0
----------------------------- × 2
2x² + 9x + 8 = 0