# Entrance exams

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Let x=[3 1 2].Which of the following statements are true? {Multiple correct options}

a)x’x is a 3×3 matrix.

b)xx’ is a 3×3 matrix.

c)xx’ is a 1×1 matrix.

d)xx’=x’x.

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Given: x=[3,1,2]. Now x’= is column vector with 3 rows where the entities are 3,1,2.

According to matrix multiplication rule x’x yields a 3*3 matrix :

9 3 6

3 1 2

6 2 4

Also, xx’ is a scalar i.e., a 1*1 matrix i.e., xx’=14

Hence options a) and c) are the correct ones.