If A = [8(0 2 3 -4)] and kA = [8(0 3a 2b 24)], then the values of ๐‘˜,๐‘Ž and ๐‘ respectively are:

(a) −6, −12, −18          (b) −6, −4, −9

(c) −6, 4, 9                   (d) −6, 12, 18

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  1. Class 12
  2. Solutions of Sample Papers and Past Year Papers - for Class 12 Boards

Transcript

Question 32 If A = [โ– 8(0&2@3&โˆ’4)] and kA = [โ– 8(0&3๐‘Ž@2๐‘&24)], then the values of ๐‘˜,๐‘Ž and ๐‘ respectively are: (a) โˆ’6, โˆ’12, โˆ’18 (b) โˆ’6, โˆ’4, โˆ’9 (c) โˆ’6, 4, 9 (d) โˆ’6, 12, 18 Now, A = [โ– 8(0&2@3&โˆ’4)] kA = k [โ– 8(0&2@3&โˆ’4)] kA = [โ– 8(0 ร— ๐‘˜&2 ร— ๐‘˜@3 ร— ๐‘˜&โˆ’4 ร— ๐‘˜)] kA = [โ– 8(0&2๐‘˜@3๐‘˜&โˆ’4๐‘˜)] Putting value of kA [โ– 8(0&3๐‘Ž@2๐‘&24)] = [โ– 8(0&2๐‘˜@3๐‘˜&โˆ’4๐‘˜)] Thus, 24 = โˆ’4k โˆ’4k = 24 k = 24/(โˆ’4) k = โˆ’6 Also, 3a = 2k 3a = 2(โˆ’6) 3a = โˆ’12 a = (โˆ’12)/3 a = โˆ’4 So, the correct answer is (B) [โ– 8(0&3๐‘Ž@2๐‘&24)] = [โ– 8(0&2๐‘˜@3๐‘˜&โˆ’4๐‘˜)] Thus, 24 = โˆ’4k โˆ’4k = 24 k = 24/(โˆ’4) k = โˆ’6 Also, 3a = 2k 3a = 2(โˆ’6) 3a = โˆ’12 a = (โˆ’12)/3 a = โˆ’4 2b = 3k 2b = 3(โˆ’6) 2b = โˆ’18 b = (โˆ’18)/2 b = โˆ’9 Thus, k = โˆ’6, a = โˆ’4, b = โˆ’9 So, the correct answer is (B)

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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.