11th And 12th > Mathematics
MATRICES MCQs
Total Questions : 69
| Page 1 of 7 pages
Answer: Option B. ->
α=a2+b2,β=2ab
:
B
A2=[αββα]=[abba][abba];α=α2+b2;β=2ab
:
B
A2=[αββα]=[abba][abba];α=α2+b2;β=2ab
Answer: Option B. ->
cos2θ2.AT
:
B
|A|=1+tan2θ2=sec2θ2AB=I⇒B−IA−1[1001]⎡⎢⎣1−tanθ2tanθ21⎤⎥⎦sec2θ2=cos2θ2.AT.
:
B
|A|=1+tan2θ2=sec2θ2AB=I⇒B−IA−1[1001]⎡⎢⎣1−tanθ2tanθ21⎤⎥⎦sec2θ2=cos2θ2.AT.
Answer: Option C. ->
A+B′
:
C
We can see from the options that if we take transpose of B,
B′ will be of 2 x 3 matrix which cannot be added to a 3 x 3 matrix, as for the addition the order should be the same.
:
C
We can see from the options that if we take transpose of B,
B′ will be of 2 x 3 matrix which cannot be added to a 3 x 3 matrix, as for the addition the order should be the same.
Answer: Option C. ->
⎡⎢⎣an000bn000cn⎤⎥⎦
:
C
Since A2=A.A=⎡⎢⎣a000b000c⎤⎥⎦⎡⎢⎣a000b000c⎤⎥⎦=⎡⎢⎣a2000b2000c2⎤⎥⎦
And A3=⎡⎢⎣a3000b3000c3⎤⎥⎦,....⇒An=An−1.A=⎡⎢⎣an−1000bn−1000cn−1⎤⎥⎦⎡⎢⎣a000b000c⎤⎥⎦=⎡⎢⎣an000bn000cn⎤⎥⎦.
Note: Students should remember this question as a formula.
:
C
Since A2=A.A=⎡⎢⎣a000b000c⎤⎥⎦⎡⎢⎣a000b000c⎤⎥⎦=⎡⎢⎣a2000b2000c2⎤⎥⎦
And A3=⎡⎢⎣a3000b3000c3⎤⎥⎦,....⇒An=An−1.A=⎡⎢⎣an−1000bn−1000cn−1⎤⎥⎦⎡⎢⎣a000b000c⎤⎥⎦=⎡⎢⎣an000bn000cn⎤⎥⎦.
Note: Students should remember this question as a formula.
Answer: Option A. ->
3×4
:
A
A3×4⇒A′4×3Now A'B defined
⇒Bis 3×p
Again B3×pA′4×3 defined ⇒p=4
∴B is 3×4.
:
A
A3×4⇒A′4×3Now A'B defined
⇒Bis 3×p
Again B3×pA′4×3 defined ⇒p=4
∴B is 3×4.
Answer: Option C. ->
A(z)=A(x)A(y)
:
C
A(z)=A(x+y1+xy)=[1+xy(1−x)(1−y)] ⎡⎢⎣1−(x+y1+xy)−(x+y1+xy)1⎤⎥⎦
∴A(x).A(y)=A(z)
:
C
A(z)=A(x+y1+xy)=[1+xy(1−x)(1−y)] ⎡⎢⎣1−(x+y1+xy)−(x+y1+xy)1⎤⎥⎦
∴A(x).A(y)=A(z)
Answer: Option D. ->
[10−n1]
:
D
A=[cosθsinθsinθ−cosθ]AAT=I (i)Now,C=ABAT⇒ATC=BAT (ii)Now ATCnA=ATC.Cn−1A=BATCn−1A(from(ii))=BATC.Cn−2A=B2ATCn−2A=.......=Bn−1ATCA=Bn−1BATA=Bn=[10−n1]
:
D
A=[cosθsinθsinθ−cosθ]AAT=I (i)Now,C=ABAT⇒ATC=BAT (ii)Now ATCnA=ATC.Cn−1A=BATCn−1A(from(ii))=BATC.Cn−2A=B2ATCn−2A=.......=Bn−1ATCA=Bn−1BATA=Bn=[10−n1]
Answer: Option A. ->
Both A−1B and A−1B−1 are symmetric
:
A
AB =BA
Previous & past multiplying both sides by A−1.
A−1(AB)A−1=A−1(BA)A−1(A−1A)(BA−1)=A−1B(AA−1)⇒(BA−1)1=(A−1B)1=(A−1)1B1(reversal laws)=A−1B(as B=B1)(A−1)1=A−1⇒A−1B is symmetric
Similarly for A−1B−1.
:
A
AB =BA
Previous & past multiplying both sides by A−1.
A−1(AB)A−1=A−1(BA)A−1(A−1A)(BA−1)=A−1B(AA−1)⇒(BA−1)1=(A−1B)1=(A−1)1B1(reversal laws)=A−1B(as B=B1)(A−1)1=A−1⇒A−1B is symmetric
Similarly for A−1B−1.
Answer: Option C. ->
skew symmetric matrix
:
C
aji=j2−i2=−(i2−j2)=−aij
:
C
aji=j2−i2=−(i2−j2)=−aij
Answer: Option C. ->
A - I is non zero singular
:
C
A2=I⇒A2−I=0
⇒ (A+I)(A-I)=0
∴ either |A+I|=0 or
|A−I|=0
If |A−I|≠0, then (A+I)(A−I)=0⇒A+I=0 which is not so
∴|A−I| and A−I≠0.
:
C
A2=I⇒A2−I=0
⇒ (A+I)(A-I)=0
∴ either |A+I|=0 or
|A−I|=0
If |A−I|≠0, then (A+I)(A−I)=0⇒A+I=0 which is not so
∴|A−I| and A−I≠0.