Solution to Exercise 3.11.
A mathematician is a device for turning coffee into theorems.
—Paul Erdős (1913–1996)

Exercise 3.11. Find the line l[l₁, l₂, l₃] that contains the points (3, 5, 1) and (–7, 3, 1).

Hence, by Proposition 3.1, the equation of the line is  Evaluate the determinant to obtain x₁ – 5x₂ + 22 = 0. Thus the line is [1, –5, 22].