**
Question 24 (OR 1
**
**
st
**
**
question)
**

If A = [3 1 2 3 2 -3 2 0 -1], find A
^{
–1
}

Hence, solve the system of equations:

3x + 3y + 2z = 1

x + 2y = 4

2x – 3y – z = 5

Last updated at Oct. 1, 2019 by

**
Question 24 (OR 1
**
**
st
**
**
question)
**

If A = [3 1 2 3 2 -3 2 0 -1], find A
^{
–1
}

Hence, solve the system of equations:

3x + 3y + 2z = 1

x + 2y = 4

2x – 3y – z = 5

Transcript

Question 24 (OR 1st question) If A = [■8(3&1&2@3&2&−3@2&0&−1)], find A–1 Hence, solve the system of equations: 3x + 3y + 2z = 1 x + 2y = 4 2x – 3y – z = 5 For our equation [■8(3&3&2@1&2&0@2&−3&−1)][■8(𝑥@𝑦@𝑧)] = [■8(1@4@5)] i.e. (𝐴^𝑇)X = B X = 〖(𝐴^𝑇)〗^(−1) 𝐵 X = 〖(𝐴^(−1))〗^𝑇 𝐵 (Because 〖(𝐴^𝑇)〗^(−1) = 〖(𝐴^𝑇)〗^(−1)) Here, A = [■8(3&1&2@3&2&−3@2&0&−1)] , X = [■8(𝑥@𝑦@𝑧)] & B = [■8(1@4@5)] Finding A–1 We know that A-1 = 1/(|A|) adj (A) Calculating |A|= |■8(3&1&2@3&2&−3@2&0&−1)| = 3(−2 + 0) − 1 (–3 + 6) + 2 (0 – 4) = –6 – 3 – 8 = −17 Since |A|≠ 0 ∴ The system of equation is consistent & has a unique solutions Now finding adj (A) adj A = [■8(A11&A12&A13@A21&A22&A23@A31&A32&A33)]^′ = [■8(A11&A21&A31@A12&A22&A32@A13&A23&A33)] A = [■8(3&1&2@3&2&−3@2&0&−1)] 𝐴11 = −2 + 0 = –2 𝐴12 = −[−3−(−6)] = − (−3+ 6) = −3 𝐴13 = 0 − 4 = – 4 𝐴21 = –[−1−0] = 1 𝐴22 = −3 – 4 = –7 𝐴23 = –[0−2] = 2 𝐴31 = −3−4= –7 𝐴32 = –[−9−6] = 15 𝐴33 = 6−3 = 3 Thus adj A = [■8(−2&1&−7@−3&−7&15@−4&2&3)] & |A| = –17 Now, A-1 = 1/(|A|) adj A A-1 = 1/(−17) [■8(−2&1&−7@−3&−7&15@−4&2&3)] = 1/17 [■8(2&−1&7@3&7&−15@4&−2&−3)] Now, X = 〖(𝐴^(−1))〗^𝑇 𝐵 [■8(𝑥@𝑦@𝑧)] = 1/17 [■8(2&−1&7@3&7&−15@4&−2&−3)]^′ [■8(1@4@5)] [■8(𝑥@𝑦@𝑧)] = 1/17 [■8(2&3&4@−1&7&−2@7&−15&−3)][■8(1@4@5)] " " [■8(𝑥@𝑦@𝑧)]" =" 1/17 [█(2(1)+3(4)+4(5)@−1(1)+7(4)+(−2)(5)@7(1)+(−15)(4)+(−3)(5))] " " [■8(𝑥@𝑦@𝑧)]" =" 1/17 [■8(2+12+20@−1+28−10@7−60−15)] " " [■8(𝑥@𝑦@𝑧)]" =" 1/17 [■8(34@17@−68)] " " [■8(𝑥@𝑦@𝑧)]" =" [■8(2@1@−4)] "∴ x = 2, y = 1 and z = "–4

CBSE Class 12 Sample Paper for 2019 Boards

Paper Summary

Question 1 Important

Question 2

Question 3

Question 4 (Or 1st) Important

Question 4 (Or 2nd)

Question 5

Question 6

Question 7 Important

Question 8 (Or 1st) Important

Question 8 (Or 2nd)

Question 9

Question 10 (Or 1st) Important

Question 10 (Or 2nd)

Question 11 Important

Question 12 (Or 1st)

Question 12 (Or 2nd)

Question 13 (Or 1st) Important

Question 13 (Or 2nd)

Question 14 Important

Question 15

Question 16 (Or 1st)

Question 16 (Or 2nd) Important

Question 17

Question 18

Question 19 Important

Question 20 Important

Question 21 (Or 1st)

Question 21 (Or 2nd) Important

Question 22

Question 23 Important

Question 24 (Or 1st) You are here

Question 24 (Or 2nd) Important

Question 25

Question 26 (Or 1st) Important

Question 26 (Or 2nd)

Question 27 (Or 1st) Important

Question 27 (Or 2nd) Important

Question 28

Question 29 Important

Class 12

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

About the Author

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.