3. Suppose 1 0 2 02 a 0 0 b 2R₂ 2R2-5R3 R2-R3 R₁+2R³ R. AR2-2R1, R₁-3R1, (a) (4 points) Determine the the values of a and b such that A is singular. Explain how you get the answer. (b) (4 points) Suppose R = I3 the order 3 identity matrix. Write A as a product of elementary matrices. (c) (2 points) Suppose det(A) = -20. What is det (R)? Show your workings.

Fig: 1