1. B

2. B

Penjelasan dengan langkah-langkah:

1. 2x²+ 4x - 8 = 0

x1 + x2 = -b/a = -4/2.1 = -2

x1 . x2 = c/a = -8/2 = -4

akar akar baru (x1 + 2) dan (x2 + 2)

(x1 + 2) + (x2 + 2) = (x1 + x2) + 4

= -2 + 4

= 2

(x1 + 2) . (x2 + 2) = x1.x2 + 2(x1+x2) + 4

= -4 + 2.(-2) + 4

= -4 - 4 + 4

= -4

persamaan baru

x² - 2x + (-4) = 0

x² - 2x - 4 = 0

2. persamaan lewat (-3,0) dan (1,0)

maka x1 = -3, x2 = 1

f(x) = a(x - (-3))(x - 1)

= a(x + 3)(x - 1)

= a(x² + 2x - 3)

mencari nilai a , lewat (-1,8)

f(-1) = 8

a((-1)² + 2(-1) - 3) = 8

a(1 - 2 - 3) = 8

a(-4) = 8

a = 8/-4 = -2

maka petsamaan kuadratnya

f(x) = -2(x² + 2x - 3)

= -2x² - 4x + 6