tolong di jawab para mastah

Rumus akar-akar --->
x1 + x2 = -b/a = -1/1 = -1
x1 . x2 = c/a = -2/1 = -2

nilai {(x1 +x2)^2  - 2(x1.x2)} / x1.x2 = {(-1)^2 - 2(-2)} / -2 = (1 + 4)/-2 = -5/2

maaf kalau salah, semoga membantu :)