tolong dibantu no 20 dan 21 dengan caranya..

Bab Fungsi Kuadrat dan differensial
Matematika SMA Kelas XI

20] y = a(x - x1) (x - x2)
1 = a (0 - 1) (0 - (-2))
1 = a (-1) . 2
a = -1/2

y = a (x - x1) (x - x2)
y = (1/2) (x - 1) (x + 2)
y = (1/2) (x² + x - 2)
y = (1/2) x² + (1/2) x - 1

jawabannya B

21] y = (x²/2) - (3/x²)
y = (x²/2) - (3x⁻²)
y' = (2x/2) - (-2 . 3 . x⁻³)
y' = x + 6/x³