1
WB JEE 2023
MCQ (Single Correct Answer)
+1
-0.25
Change Language

If the n terms $${a_1},{a_2},\,......,\,{a_n}$$ are in A.P. with increment r, then the difference between the mean of their squares & the square of their mean is

A
$${{{r^2}\{ {{(n - 1)}^2} - 1\} } \over {12}}$$
B
$${{{r^2}} \over {12}}$$
C
$${{{r^2}({n^2} - 1)} \over {12}}$$
D
$${{{n^2} - 1} \over {12}}$$
2
WB JEE 2023
MCQ (Single Correct Answer)
+1
-0.25
Change Language

If $$1,{\log _9}({3^{1 - x}} + 2),{\log _3}({4.3^x} - 1)$$ are in A.P., then x equals

A
$${\log _3}4$$
B
$$1 - {\log _3}4$$
C
$$1 - {\log _4}3$$
D
$${\log _4}3$$
3
WB JEE 2023
MCQ (Single Correct Answer)
+1
-0.25
Change Language

Reflection of the line $$\overline a z + a\overline z = 0$$ in the real axis is given by :

A
$$az + \overline {az} = 0$$
B
$$\overline a z - a\overline z = 0$$
C
$$az - \overline {az} = 0$$
D
$${a \over z} + {{\overline a } \over z} = 0$$
4
WB JEE 2023
MCQ (Single Correct Answer)
+1
-0.25
Change Language

If one root of $${x^2} + px - {q^2} = 0,p$$ and $$q$$ are real, be less than 2 and other be greater than 2, then

A
$$4 + 2p + {q^2} > 0$$
B
$$4 + 2p + {q^2} < 0$$
C
$$4 + 2p - {q^2} > 0$$
D
$$4 + 2p - {q^2} < 0$$
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