All pencil problems follow the same five-step scheme.

In summary — General method for pencil problems

  1. Recognise whether the pencil is proper or improper by collecting the parameter; identify the two generators.
  2. Translate the geometric condition into an equation or inequality in kk.
  3. Solve for kk.
  4. Check the generator excluded from the parametrisation.
  5. Write the solution lines by substituting the values of kk found.

Topics: Pencils of lines
Concepts: Pencil of lines · Improper pencil · Proper pencil · Generators · Pencil parameter
Functions: Line
Skills: Analytic geometry · Solving equations