bantuin dong . akar persamaan kuadrat.

persamaan kuadrat yg akar2nya x1 dan x2 adalah
x² - (x1+x2)x + (x1.x2) = 0
x1 = 3x1 - 1
x2 = 3x2 - 1
dimana :
x1 + x2 = -b/a = -(-1)/3 = ⅓
x1 . x2 = c/a = -5/3

x1 + x2 = 3x1 - 1 + 3x2 - 1 = 3x1 + 3x2 - 2
= 3(x1 + x2) - 2
= 3(⅓) - 2
= 1 - 2
= -1
x1 . x2 = (3x1 - 1)(3x2 - 1) = 3x1.3x2 - 3x1 - 3x2 + 1
= 9(x1.x2) - 3(x1 + x2) + 1
= 9(-5/3) - 3(⅓) + 1
= -15 - 1 + 1
= -15

maka persamaan
x² - (-1)x - 15 = 0
x² + x - 15 = 0