This test has 8 questions worth 20 points in total and takes about 45 minutes. Give exact answers unless a decimal is requested, and show each step of a factorization. A calculator is allowed for decimal approximations.
- Grade: Precalculus
- Chapter: Complex Factorization and Volume of a Sphere
- Common Core: N-CN.C.8, G-GMD.A.2
- Time: 45 minutes
- Total: 20 points (Question 1: 2 pts; Question 2: 2 pts; Question 3: 2 pts; Question 4: 3 pts; Question 5: 3 pts; Question 6: 3 pts; Question 7: 2 pts; Question 8: 3 pts)
Question 1: Powers of i (2 points)
Simplify.
- \(i^{38}\) (1 point)
- \(i^{55}\) (1 point)
Question 2: Factor a sum of squares (2 points)
Factor \(25x^{2}+4\) over the complex numbers. (1 point) Then expand your answer to verify it. (1 point)
Question 3: Solve over the complex numbers (2 points)
Solve.
- \(x^{2}+64=0\) (1 point)
- \(x^{2}+18=0\) (1 point)
Question 4: Fourth-degree factorization (3 points)
Factor \(x^{4}-256\) completely over the complex numbers.
Question 5: Quadratic with no real zeros (3 points)
The graph of \(y=x^{2}-6x+25\) is shown.
- Explain from the graph why the quadratic has no real zeros. (1 point)
- Factor \(x^{2}-6x+25\) over the complex numbers. (2 points)
Question 6: Matching cross-sections (3 points)
A hemisphere of radius \(5\) ft and a cylinder of radius \(5\) ft and height \(5\) ft with a cone removed are each cut by a plane \(3\) ft above their base.
- Find the area of the cross-section of the hemisphere. (1 point)
- Find the area of the cross-section of the cylinder with the cone removed. (1 point)
- State what Cavalieri’s principle concludes if this holds at every height. (1 point)
Question 7: Volume from a cylinder and a cone (2 points)
A cylinder and a cone each have radius \(6\) in. and height \(6\) in.
- Find the volume of the cylinder with the cone removed. (1 point)
- Use that result to find the volume of a sphere of radius \(6\) in. (1 point)
Question 8: Spherical tank (3 points)
A spherical storage tank has a diameter of \(20\) ft.
- Find its exact volume. (1 point)
- Find its volume to the nearest tenth of a cubic foot. (1 point)
- Find the capacity in gallons to the nearest gallon, using 1 cubic foot = 7.48 gallons. (1 point)
See every chapter on the Precalculus math page.



