Which of the following statements are true? I. The space P_2 is a subspace of P_3. II. The set of polynomials of the form a_2t^2 + a_1t + a_0 with a_2a_1a_0 = 0 is a subspace of P_2. III. The set of polynomials of the form a_2t^2 + a_1t + a_0 with a_2 + 2 = a_1 + a_0 + 2 is a subspace of P_2. A. I only B. II only C. I and III D. II and III E. I, II and III Solution Let us analyze all these statements one by one Statement I : We know that standard basis for P2 is {1, x, x^2} and standard basis for P3 is {1,x,x^2,x^3}. And P2 closed on vector addition, scalar multiplication over P3 (and it already contails zero vector), therefore, P2 is indeed a subspace of P3. Therefore, statement I is true. Statement II : Set of polynomials a2t2+a1t+a0 with a2a1a0 = 0 would mean that one of a2, a1 and a0 must be zero. If either of a2, a1 or a0 be zero, then using a linear combination, we can get a vector that will have all three components. But as per the given condition, our set can have polynomials with only two components. Therefore, the given set is not closed under vector addition. Therefore, Statement II is false. Statement III : Set of polynomials a2t2+a1t+a0 with a2+2 = a1+a0+2. We can write a2+2 = a1+a0+2 as a2 = a1+a0 Then, the vector a2t2+a1t+a0 becomes (a1+a0)t2+a1t+a0 This set is closed under vector addition as well as scalar multiplication and it also contains vector 0, therefore, it forms a subspace of P2. Hence statement III is true. Therefore, C is the correct option!.