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If A=[(2,-2,-4),(-1,3,4),(1,-2,x)] is an...

If `A=[(2,-2,-4),(-1,3,4),(1,-2,x)]` is an idempotent matrix, then x equals :

A

`-5`

B

`-1`

C

`-3`

D

`-4`

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The correct Answer is:
C
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MODERN PUBLICATION-UNIT TEST PAPER NO - 4 -SELECT THE CORRECT ANSWER
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  2. If 0 lt x lt 1", then " sqrt(1+x^(2))[{x cos (cot^(-1)x) + sin ( cot...

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  3. If A=[(2,-2,-4),(-1,3,4),(1,-2,x)] is an idempotent matrix, then x equ...

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  4. The value of the determinant |[loga(x/y), loga(y/z), loga(z/x)], [logb...

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  5. If alpha , beta , gamma are the roots of x^3+px+q=0 , then the value o...

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  6. If alpha,beta are the roots of the equation ax^2+bx+c=0 and Sn=alpha^n...

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  7. if A=[[cos,sinx,0],[-sinx,cosx,0],[0,0,1]]=f(x) then A^-1

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  8. Consider the system of linear equations: x(1) + 2x(2) + x(3) = 3 2...

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  9. Let a,b and c be such that (b+c) ne 0 . If |(a,a+1,a-1),(-b,b+1,b-1)...

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  10. Let a,b,c, be any real number. Suppose that there are real numbers x,y...

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  11. If D = |(1,1,1),(1,1 +x,1),(1,1,1 +y)| " for " x!= 0, y != 0, then D i...

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  12. The system of equations alphax+y+z=alpha-1, x+alphay+z=alpha-1, x+y+al...

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  13. If a^(2)+b^(2)+c^(2)=-2 and |{:(1+a^(2)x,(1+b^(2))x,(1+c^(2))x),((...

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  14. If a1, a2, a3,....... are in G.P. then the value of determinant |(log(...

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  15. Given , 2x-y+2z=2, x-2y+z=-4, x+y+lambdaz=4, then the value of lam...

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  17. If 1,omega,omega^2 are the cube roots of unity , then Delta=|(1,ome...

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  18. The number of values of k, for which the system of eauations: (k+1)x...

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  19. Let omega = - (1)/(2) + i (sqrt3)/(2), then the value of the determina...

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  20. If a gt 0 and discriminant of ax^(2) + 2bx + c is negative, then Del...

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