Diketahui f(x)=1/3x³-x²-8x+10

→ f(1) = 1/3.1³-1²-8.1+10
→ f(1) = 4/3

→ Gradien garis singgung :
→ m = f'(x)
⇔m = x²-2x-8
→ Jika x = 1
⇔m = 1²-2.1-8
⇔m = 1-2-8
⇔m = -11

→ Persamaan garis singgung dengan gradien -11 dan melalui titik (1, 4/3) :
→ y- 4/3 = -11(x-1)
⇔y- 4/3 = -11x+11
⇔3y-4 = -33x+33
⇔33x+3y = 37

∴ Garis singgungnya 33x+3y = 37