1
WB JEE 2018
MCQ (Single Correct Answer)
+1
-0.25
Change Language
If $${b_1}{b_2} = 2({c_1} + {c_2})$$ and b1, b2, c1, c2 are all real numbers, then at least one of the equations $${x^2} + {b_1}x + {c_1} = 0$$ and $${x^2} + {b_2}x + {c_2} = 0$$ has
A
real roots
B
purely imaginary roots
C
roots of the form a + ib (a, b$$ \in $$R, ab $$ \ne $$ 0)
D
rational roots
2
WB JEE 2018
MCQ (Single Correct Answer)
+1
-0.25
Change Language
The number of selection of n objects from 2n objects of which n are identical and the rest are different, is
A
2n
B
2n $$-$$ 1
C
2n $$-$$ 1
D
2n $$-$$ 1 + 1
3
WB JEE 2018
MCQ (Single Correct Answer)
+1
-0.25
Change Language
If (2 $$ \le $$ r $$ \le $$ n), then $${}^n{C_r}$$ + 2 . $${}^n{C_{r + 1}}$$ + $${}^n{C_{r + 2}}$$ is equal to
A
2 . $${}^n{C_{r + 2}}$$
B
$${}^{n + 1}{C_{r + 1}}$$
C
$${}^{n + 2}{C_{r + 2}}$$
D
$${}^{n + 1}{C_r}$$
4
WB JEE 2018
MCQ (Single Correct Answer)
+1
-0.25
Change Language
The number (101)100 $$-$$ 1 is divisible by
A
104
B
106
C
108
D
1012
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