Exercises 1.1.76, 1.5.14 were graded out of three points, 1.3.36 out of four points. Common mistakes for the first two include lack of justification in 1.1.76, and forgetting to name the axes in 1.5.14.

In 1.3.36, remember that the cosine is a periodic function, so the equation cos(2x) = -1 has infinitely many solutions. Also in part (c), you cannot divide by x - 1 without assuming that x is not -1, so -1 is not in the domain.