1
WB JEE 2016
MCQ (Single Correct Answer)
+2
-0.5
If $$\alpha$$ and $$\beta$$ are roots of ax2 + bx + c = 0, then the equation whose roots are $$\alpha$$2 and $$\beta$$2, is
A
a2x2 $$-$$ (b2 $$-$$ 2ac) x + c2 = 0
B
a2x2 + (b2 $$-$$ ac) x + c2 = 0
C
a2x2 + (b2 + ac) x + c2 = 0
D
a2x2 + (b2 + 2ac) x + c2 = 0
2
WB JEE 2016
MCQ (Single Correct Answer)
+2
-0.5
If $$\omega$$ is an imaginary cube root of unity, then the value of (2 $$-$$ $$\omega$$) (2 $$-$$ $$\omega$$2) + 2(3 $$-$$ $$\omega$$)(3 $$-$$ $$\omega$$2) + ... + (n $$-$$ 1) (n $$-$$ $$\omega$$)(n $$-$$ $$\omega$$2) is
A
$${{{n^2}} \over 4}{(n + 1)^2} - n$$
B
$${{{n^2}} \over 4}{(n + 1)^2} + n$$
C
$${{{n^2}} \over 4}{(n + 1)^2}$$
D
$${{{n^2}} \over 4}(n + 1) - n$$
3
WB JEE 2016
MCQ (Single Correct Answer)
+2
-0.5
If $${}^n{C_{r - 1}} = 36,{}^n{C_r} = 84$$ and $${}^n{C_{r + 1}} = 126$$, then the value of $${}^n{C_8}$$ is
A
10
B
7
C
9
D
8
4
WB JEE 2016
MCQ (Single Correct Answer)
+2
-0.5
In a group of 14 males and 6 females. 8 and 3 of the males and females, respectively are aged above 40 yr. The probability that a person selected at random from the group is aged above 40 yr given that the selected person is a female, is
A
$${2 \over 7}$$
B
$${1 \over 2}$$
C
$${1 \over 4}$$
D
$${5 \over 6}$$
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