Răspuns:
ecuatia tangentei la Gf in punctul x₀ :
y-f(x₀)=f'(x₀)·(x-x₀)
f(x) = x²-2x ⇒ f'(x) = 2x -2
x₀ = -1
f(-1)=1+2=3
f'(-1)= -2 -2 = -4
y -3 = -4(x+1) ⇔ y = -4x-1
