questionr
Early access
Exams
Joint Entrance Examination
Mathematics
Matrices and Determinants
Question 75
Question 75 of 472
Medium
MCQ
A
=
[
[
∣
1
0
0
0
α
β
0
β
α
]
]
∣
∣
2
A
∣
3
=
2
21
α
,
β
∈
Z
α
A=[[|\begin{gathered} 1 \quad 0 \quad 0 \\ 0 \quad \alpha \quad \beta \\ 0 \quad \beta \quad \alpha \end{gathered}]]||2A{|}^{3}={2}^{21}\alpha ,\beta \in Z\alpha
A
=
[[
∣
1
0
0
0
α
β
0
β
α
]]
∣∣2
A
∣
3
=
2
21
α
,
β
∈
Z
α
A
9
B
17
C
3
D
5
Check answer
Press A-D to select · Enter to check
Solutions · 1
Post your solution
Official solution
∣
A
∣
=
α
2
−
β
2
∣
2
A
∣
3
=
2
21
⇒
∣
A
∣
=
2
4
α
2
−
β
2
=
16
(
α
+
β
)
(
α
−
β
)
=
16
⇒
α
=
45
\begin{gathered} |A|={\alpha }^{2}-{\beta }^{2} \\ |2A{|}^{3}={2}^{21}\Rightarrow |A|={2}^{4} \\ {\alpha }^{2}-{\beta }^{2}=16 \\ (\alpha +\beta )(\alpha -\beta )=16\Rightarrow \alpha =45 \end{gathered}
∣
A
∣
=
α
2
−
β
2
∣2
A
∣
3
=
2
21
⇒
∣
A
∣
=
2
4
α
2
−
β
2
=
16
(
α
+
β
)
(
α
−
β
)
=
16
⇒
α
=
45
Answer the question to unlock
Previous
Next