# Ex 4.2, 15 - Chapter 4 Class 12 Determinants

Last updated at Jan. 22, 2020 by Teachoo

Last updated at Jan. 22, 2020 by Teachoo

Transcript

Ex 4.2, 15 Choose the correct answer. Let A be a square matrix of order 3 ร 3, then |"kA" | is equal to A. "k" |"A" | B. "k" 2|"A" | C. "k" 3|"A" | D. 3"k" |"A" | Let A = [โ 8(๐1&๐1&๐1@๐2&๐2&๐2@๐3&๐3&๐3)]_(3 ร 3) We need to find |kA| kA = k [โ 8(๐1&๐1&๐1@๐2&๐2&๐2@๐3&๐3&๐3)] = [โ 8(๐๐1&๐๐1&๐๐1@๐๐2&๐๐2&๐๐2@๐๐3&๐๐3&๐๐3)] If a matrix is multiplied by a constant, then constant is multiplied to all elements of matrix |"kA" | = |โ 8(๐๐1&๐๐1&๐๐1@๐๐2&๐๐2&๐๐2@๐๐3&๐๐3&๐๐3)| Taking out k common from R1 R2 & R3 = k. k. k |โ 8(a1&b1&c1@a2&b2&c2@a3&b3&c3)| = k3 |โ 8(a1&b1&c1@a2&b2&c2@a3&b3&c3)| = k3 |A| Thus, Correct answer is C Property: If each element of row of determinant is multiplied by a constant k , then its value get multiplied by k

Ex 4.2

Chapter 4 Class 12 Determinants

Serial order wise

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Davneet Singh

Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 10 years. He provides courses for Maths and Science at Teachoo.