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≠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 : 13
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 : 14
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 : 15
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 : 16
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 : 17
3 If a + b + c = 0, then the value of
1 1 2 0 3 3 4 -1 Go to Discussion
Solution Qus : 18
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 : 19
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
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