If `A=[a_(ij)]_(mxxn)` and `a_(ij)=(i^(2)+j^(2)-ij)(j-i)`, `n` odd, then which of the following is not the value of `Tr(A)`
A. `0`
B. `|A|`
C. `2|A|`
D. none of these
Correct Answer - D
`(d)` AS `a_(ij)=(i^(2)+j^(2)-ij)(j-i)`
`a_(ji)=(j^(2)+i^(2)-ji)(i-j)=-a_(ij)`
`impliesA` is skew symmetric `impliesT_(r )(A)=0`
Also `|A|=0`
Correct Answer - D
If A is nth root of `I_(2)`, then `A^(n)=I_(2)`. Now,
`A^(2)=[(a,b),(0,a)][(a,b),(0,a)]=[(a^(2),2ab),(0,a^(2))]`
`A^(3)=A^(2) A=[(a^(2),2ab),(0,a^(2))][(a,b),(0,a)]=[(a^(3),3a^(2)b),(0,a^(3))]`
Thus, `A^(n)=[(n^(n),na^(n-1)b),(0,a^(n))]`
Now,
`A^(n)=I implies [(a^(n),na^(n-1)b),(0,a^(n))]=[(1,0),(0,1)]`
`implies a^(n)=1, b=0`
Correct Answer - C
As second row of all the options is same, we have to look at the elements of the first row. Let the left inverse be `[(a,b,c),(d,e,f)]`. Then...
Correct Answer - A::C
Given equation is `x^(2) + 2x sin(cos^(-1) y) + 1 =0`
Since x is real, `D ge 0`. Therefore,
`4(sin(cos^(-1)y))^(2) -4 ge 0`
or `(sin(cos^(-1)y))^(2) ge 1`...
`sin^2theta_1+sin^2theta_2+sin^2theta_3=0`
`rArr sin^2theta_1=sin^2theta_2=sin^2theta_3=0`
`rArr cos^2theta_1,cos^2theta_2,cos^2theta_3=1`
`rArr costheta_1,costheta_2,costheta_3=pm1`
`cos^2theta_1+cos^2theta_2+cos^2theta_3"can be-3 (when all are -I)"`
or 3 (when all are +I)
or -1 (when any two are -1 and one is +1)...
Correct Answer - B
`(b)` We have `S_(n)-S_(n-2)=T_(n)+T_(n-1)` (Taking `n` to be odd)
`:.T_(n-1)(1+(T_(n))/(T_(n-1)))=((n+1)/(2))-((n-1))/(2)=1` (As `S_(n)=(n+1)/(2)`, if `n` is odd)
`:.T_(n-1)(1+(n^(2))/(1-n^(2)))=1`
`:.T_(n-1)=-(n^(2)-1)` when `n` is odd
Also, `S_(m)=S_(m-1)+T_(m)`
If `m` is...