Tolong bantuan nya ya, nomor 12 dan 13

-2x² + 7x + 15
2x² -7x – 15
(2x+ 3) (x – 5) = 0
x1 = -3/2 x2 = 5

6×1 + 4×2 = 6(-3/2) + 4(5) =
= -9 +20
= 11

x²+6x+2
x1+x2 = -b/a = -6
x1.x2 = 2

3×1 dan 3×2
= 3(x1+x2 = -18
= 9(x1.x2) = 18

PKB = x² – 3(x1+x2)x + 9×1.x2 = 0
PKB = x² +18x +18 = 0