Tuesday, 23 April 2024

REVISION MATHS- XII(24/25)

Day -3
1) Without expanding at any stage , find the value of the determinant:
∆= 2    x      y+ z 
      2    y      z + x 
      2    z      x + y

2) If M= 1     2 
               2     3 and M² - kM - I₂= 0, then find the value of k.

3) Find dy/dx , if x= at² and y= 2at.

4) Using properties of determinants, prove 
x    x²      1+ px³
y    y²      1+ py³
z    z²      1+ pz³ =
(1+ pxyz)(x - y)(y - z) (z - x) Where p is any scalar.

5) Prove that the function f(x)= |x -1|, x∈R, is continuous at x= 1.

6) If A= 3   -2   3 & B= -1  -5   -1
              2    1  -1          -8  -6    9
              4   -3   2         -10  1    7
Evaluate. Hence, solve the system of equations, 3x - 2y + 3z= 8; 2x + y - z = 1; 4x - 3y + 2z = 4.

7) Using elementary transformation, find the inverse of the matrix 
 1     3     -2
-3     0     -1
 2     1      0



Day- 2

1) If y= (cosx - since)/(cosx + since), then find dy/dx 

2) If x = a sin2t, y= a(cos2t + log tan t) then find dy/dx.

3) If A= 1.  4     x
              z   2     y
             -3  -1   3 is a symmetric Matrix, then the value of x+ y+ z is

4) If A= 3     2
              5    -7, then find inverse of A.

5) Evaluate the determinant:
 x -1         1
 x³       x²+ x +1

6) If 2     2 = 3x      1
        2     3    4x      2 then find x

7) f(x= (since)/x  + cosx,  if x≠ 0
                2                         If x= 0
Show that it continuous at x= 2.

8) If A= 2    -3      5
             3     2      -4
             1     1      -2 then find inverse of A. 
Using the inverse of A solve the following system of equations:
2x - 3y + 5z= 11
3x + 2y - 4z= -5
x + y -2z= -3.


Day-1

A) Using properties of determinants. Prove that:

a) x²    y²     z²
    x³     y³    z³
   xyz  xyz  xyz
= xyz(x - y)(y - z)(z - x)(xy+ yz+ zx)

b) y+ z    x+ y    x
    z + x   y+ x     y = x³+ y³+ z³- 3xyz
    x+ y    z + x    z 

c)    a       b - c      c- b
      a- c      b          c- a
      a - b   b - a        c
= (a+ b -c)(b+ c -a)(c +a -b)

d) (b+ c)²      a²       a²
        b²      (c +a)²    b²
        c²           c²    (a +b)²
= 2abc(a+ b+ c)³

B) If X is a 2x2 matrix given that 
1) A= 1     3 & B= 1     -1
          0     1          0      1 with the relation AX= B, find the matrix X.

2) If A= 1  2  3 B= 1   0   2 & C= 4   4   10
             -1 -3  2      3   4   5          4   2   14 with the relation 2A + kB= C find the value of k (given k≠ 0).

3) If A= 4    2
              1    1 find (A - 2I)(A - 3I), where I is a unit matrix.

4) Solve by matrix method: 5x - 12y = -9; 7x - 6y = -8.

C)1) f(x)= (1- cosx)/(x sinx), when x≠ 0
              = 2, When x=0
Find the value of m such that f(x) is continuous at x= 0.

2) Given f(x)= x²+4, x≤2 & €(x)= 2x, x ≤2
                      = x+6, x>2            = 4, x> 2.
Show that f(x) x €(x) is continuous at x= 2.

3) f(x)= {log(1+ax) - log(1- bx)}/x is not defined at x= 0; find the value of f(0) so that f(x) is continuous at x= 0.



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