Qus : 10
2
The equation (x-a)3 +(x-b)3 +(x-c)3 = 0 has
1
All three real roots
2
One real and two imaginary roots
3
Three real roots,namely x = a, x = b, x = c
4
None of these
Go to Discussion
Solution
Let f(x) = (x – a)3 + (x – b)3 + (x – c)3 .
Then f'(x) = 3{(x – a)2 + (x – b)2 + (x –c)2 }
clearly , f'(x) > 0 for all x.
so, f'(x) = 0 has no real roots.
Hence, f(x) = 0 has two imaginary and one real root
Qus : 11
4
Let
and
be the roots f the equation
and
are the roots of the equation
, then the value of r,
1
2
3
4
Go to Discussion
Solution
Qus : 12
4
If α and β are the two roots of the quadratic equation x 2 + a x + b = 0 , ( a b ≠ 0 ) then the quadratic roots whose roots 1 α 3 + α and 1 β 3 + β is
1
b ( b 2 + 1 + a 2 + 2 b ) x 2 − ( a 3 + a − 3 a b ) x + 1 = 0
2
b ( b 2 + 1 + a 2 − 2 b ) x 2 − ( a 3 + a − 3 a b ) x + 1 = 0
3
b ( b 2 + 1 + a 2 + 2 b ) x 2 + ( a 3 − a − 3 a b ) x + 1 = 0
4
b ( b 2 + 1 + a 2 − 2 b ) x 2 + ( a 3 + a − 3 a b ) x + 1 = 0
Go to Discussion
Solution
Qus : 13
4
If α≠β and α 2 = 5 α − 3 , β 2 = 5 β − 3 , then the equation whose roots are α β and β α is
1
3 x 2 − 25 x + 3 = 0
2
3 x 2 + 5 x + 3 = 0
3
3 x 2 − 5 x + 3 = 0
4
3 x 2 − 19 x + 3 = 0
Go to Discussion
Solution
Qus : 14
3
Given the equation x + y = 1 , x 2 + y 2 = 2 , x 5 + y 5 = A . Let N be the number
of solution pairs (x,y) to this system of equations. Then AN is equal to
1
7 2
2
3
3
19 2
4
2
Go to Discussion
Solution
Qus : 15
3
If α and β are the roots of the equation 2 x 2 + 2 p x + p 2 = 0 , where p is a non-zero real number, and α 4 and β 4 are the roots of x 2 − r x + s = 0 , then the roots of 2 x 2 − 4 p 2 x + 4 p 4 − 2 r = 0 are:
1
Real and unequal
2
Equal and zero
3
Imaginary
4
Equal and non-zero
Go to Discussion
Solution
Qus : 16
3
If x and y are positive real numbers satisfying the system of equations x 2 + y √ x y = 336 and y 2 + x √ x y = 112 , then x + y is:
1
√ 448
2
√ 224
3
20
4
40
Go to Discussion
Solution
Qus : 17
3
The value of k for which the equation ( k − 2 ) x 2 + 8 x + k + 4 = 0
has both real, distinct and
negative roots is
1
0
2
2
3
4
4
-4
Go to Discussion
Solution
Qus : 18
4
Roots of equation are a x 2 − 2 b x + c = 0 are n and m ,
then the value of b a n 2 + c + b a m 2 + c is
1
c/a
2
b/a
3
a/c
4
b/c
Go to Discussion
Solution
Qus : 19
3
If a + b + c = 0, then the value of
1
1
2
0
3
3
4
-1
Go to Discussion
Solution
Qus : 20
3
a , b , c are positive integers such that a 2 + 2 b 2 − 2 b c = 100 and 2 a b − c 2 = 100 . Then the value of a + b c is
1
10
2
100
3
2
4
20
Go to Discussion
Solution
Qus : 21
1
If x 2 + 2 a x + 10 − 3 a > 0 for all x ∈ R, then
1
-5
2
a<-5
3
a>5
4
2
Go to Discussion
Solution
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