1
JEE Main 2021 (Online) 24th February Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
If f : R $$ \to $$ R is a function defined by f(x)= [x - 1] $$\cos \left( {{{2x - 1} \over 2}} \right)\pi $$, where [.] denotes the greatest integer function, then f is :
A
continuous for every real x
B
discontinuous at all integral values of x except at x = 1
C
discontinuous only at x = 1
D
continuous only at x = 1
2
JEE Main 2021 (Online) 24th February Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
The population P = P(t) at time 't' of a certain species follows the differential equation

$${{dP} \over {dt}}$$ = 0.5P – 450. If P(0) = 850, then the time at which population becomes zero is :
A
$${\log _e}18$$
B
$${1 \over 2}{\log _e}18$$
C
2$${\log _e}18$$
D
$${\log _e}9$$
3
JEE Main 2021 (Online) 24th February Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
Let f : R → R be defined as f (x) = 2x – 1 and g : R - {1} → R be defined as g(x) = $${{x - {1 \over 2}} \over {x - 1}}$$. Then the composition function f(g(x)) is :
A
one-one but not onto
B
onto but not one-one
C
both one-one and onto
D
neither one-one nor onto
4
JEE Main 2021 (Online) 24th February Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
The function
f(x) = $${{4{x^3} - 3{x^2}} \over 6} - 2\sin x + \left( {2x - 1} \right)\cos x$$ :
A
increases in $$\left( { - \infty ,{1 \over 2}} \right]$$
B
decreases in $$\left( { - \infty ,{1 \over 2}} \right]$$
C
increases in $$\left[ {{1 \over 2},\infty } \right)$$
D
decreases in $$\left[ {{1 \over 2},\infty } \right)$$
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