TS EAMCET · Maths · Determinants

$A, P, B$ are $3 \times 3$ matrices. If $|- B| = 5, |B A^{T}| = 15, |P^{T} AP| = - 27$ , then one of the values of $|P|$ is

A $3$
B $- 5$
C $9$
D $6$

Verified Solution

Answer & Solution

Correct Answer

(A) $3$

Step-by-step Solution

Detailed explanation

Given, A,P,B are 3×3 matrices. And -B=5⇒B=-5 And BAT=15⇒BAT=15⇒A=-3 {as AB=AB & AT=A} Now solving PTAP=-27 and same above property we get, ⇒PTAP=-27 ⇒PTP=9 ⇒P2=9 ⇒P=±3 Then one of the values of P is 3

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.

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Match the items given in List-A with those of the items of List-B

	List-A		List-B
(A)	The vertex of the parabola $y^{2} + 4 x - 2 y + 3 = 0$ is	(I)	$(\frac{5}{4}, 1)$
(B)	The vertex of the parabola $x^{2} + 8 x + 12 y + 4 = 0$ is	(II)	$(1, \frac{5}{4})$
(C)	The focus of the parabola $y^{2} - x - 2 y + 2 = 0$ is	(III)	$(\frac{- 1}{2}, 1)$
(D)	The focus of the parabola $x^{2} - 2 x - 8 y - 23 = 0$ is	(IV)	$(1, - 1)$
		(V)	$(- 4, 1)$

The correct match is

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A,P,B are 3×3 matrices. If -B=5,BAT=15,PTAP=-27, then one of the values of P is

Step-by-step Solution

$A, P, B$ are $3 \times 3$ matrices. If $|- B| = 5, |B A^{T}| = 15, |P^{T} AP| = - 27$ , then one of the values of $|P|$ is