1
WB JEE 2017
MCQ (Single Correct Answer)
+1
-0.25
Change Language
Let z = x + iy, where x and y are real. The points (x, y) in the X-Y plane for which $${{{z + i} \over {z - i}}}$$ is purely imaginary, lie on
A
a straight line
B
an ellipse
C
a hyperbola
D
a circle
2
WB JEE 2017
MCQ (Single Correct Answer)
+1
-0.25
Change Language
If p, q are odd integers, then the roots of the equation $$2p{x^2} + (2p + q)x + q = 0$$ are
A
rational
B
irrational
C
non-real
D
equal
3
WB JEE 2017
MCQ (Single Correct Answer)
+1
-0.25
Change Language
Out of 7 consonants and 4 vowels, words are formed each having 3 consonants and 2 vowels. The number of such words that can be formed is
A
210
B
25200
C
2520
D
302400
4
WB JEE 2017
MCQ (Single Correct Answer)
+2
-0.5
Change Language
Let $$A = \left( {\matrix{ 1 & 1 & 1 \cr 0 & 1 & 1 \cr 0 & 0 & 1 \cr } } \right)$$. Then, for positive integer n, An is
A
$$\left( {\matrix{ 1 & n & {{n^2}} \cr 0 & {{n^2}} & n \cr 0 & 0 & n \cr } } \right)$$
B
$$\left( {\matrix{ 1 & 1 & {n\left( {{{n + 1} \over 2}} \right)} \cr 0 & 1 & n \cr 0 & 0 & 1 \cr } } \right)$$
C
$$\left( {\matrix{ 1 & {{n^2}} & n \cr 0 & n & {{n^2}} \cr 0 & 0 & {{n^2}} \cr } } \right)$$
D
$$\left( {\matrix{ 1 & n & {2n - 1} \cr 0 & {{{n + 1} \over 2}} & {{n^2}} \cr 0 & 0 & {{{n + 1} \over 2}} \cr } } \right)$$
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