1
WB JEE 2019
MCQ (Single Correct Answer)
+1
-0.25
Change Language
If $$A = \left( {\matrix{ 5 & {5x} & x \cr 0 & x & {5x} \cr 0 & 0 & 5 \cr } } \right)$$ and $$|A{|^2} = 25$$, then | x | is equal to
A
$${1 \over 5}$$
B
5
C
52
D
1
2
WB JEE 2019
MCQ (Single Correct Answer)
+1
-0.25
Change Language
Let A and B be two square matrices of order 3 and AB = O3, where O3 denotes the null matrix of order 3. Then,
A
must be A = O3 , B = O3
B
if A $$ \ne $$ O3, must be B $$ \ne $$ O3
C
if A = O3, must be B $$ \ne $$ O3
D
may be A $$ \ne $$ O3, B $$ \ne $$ O3
3
WB JEE 2019
MCQ (Single Correct Answer)
+1
-0.25
Change Language
Let P and T be the subsets of k, y-plane defined by

P = {(x, y) : x > 0, y > 0 and x2 + y2 = 1}

T = {(x, y) : x > 0, y > 0 and x8 + y8 < 1}

Then, P $$ \cap $$ T is
A
the void set $$\phi$$
B
P
C
T
D
P $$-$$ TC
4
WB JEE 2019
MCQ (Single Correct Answer)
+1
-0.25
Change Language
Let $$f:R \to R$$ be defined by $$f(x) = {x^2} - {{{x^2}} \over {1 + {x^2}}}$$ for all $$x \in R$$. Then,
A
f is one-one but not onto mapping
B
f is onto but not one-one mapping
C
f is both one-one and onto
D
f is neither one-one nor onto
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