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$∣∣ k=0∑n kk=0∑n ._{n}C_{k}.k k=0∑n ._{n}C_{k}.k_{2}k=0∑n ._{n}C_{k}.3_{k} ∣∣ =0$ holds for some positive integer n, then $k=0∑n k+1._{n}C_{k} $ equals

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Four person independently solve a certain problem correctly with probabilities $21 ,43 ,41 ,81 ˙$Then the probability that he problem is solve correctly by at least one of them is$256235 $b. $25621 $c. $2563 $d. $256253 $

Let $−61 <θ<−12π $ Suppose $α_{1}andβ_{1}$, are the roots of the equation $x_{2}−2xsecθ+1=0$ and $α_{2}andβ_{2}$ are the roots of the equation $x_{2}+2xtanθ−1=0$. If $α_{1}>β_{1}$ and $α_{2}>β_{2}$, then $α_{1}+β_{2}$ equals

Let $X$be a set with exactly 5 elements and $Y$be a set with exactly 7 elements. If $α$is the number of one-one function from $X$to $Y$and $β$is the number of onto function from $Y$to $X$, then the value of $5!1 (β−α)$is _____.

The quadratic equation $p(x)=0$ with real coefficients has purely imaginary roots. Then the equation $p(p(x))=0$ has A. only purely imaginary roots B. all real roots C. two real and purely imaginary roots D. neither real nor purely imaginary roots

Column 1,2 and 3 contains conics, equations of tangents to the conics and points of contact, respectively.Column I, Column 2, Column 3I, $x_{2}+y_{2}=a$, (i), $my=m_{2}x+a$, (P), $(m_{2}a ,m2a )$II, $x_{2}+a_{2}y_{2}=a$, (ii), $y=mx+am_{2}+1 $, (Q), $(m_{2}+1 −ma ,m_{2}+1 a )$III, $y_{2}=4ax$, (iii), $y=mx+a_{2}m_{2}−1 $, (R), $(a_{2}m_{2}+1 −a_{2}m ,a_{2}m_{2}+1 1 )$IV, $x_{2}−a_{2}y_{2}=a_{2}$, (iv), $y=mx+a_{2}m_{2}+1 $, (S), $(a_{2}m_{2}+1 −a_{2}m ,a_{2}m_{2}+1 −1 )$For $a=2 ,if$a tangent is drawn to a suitable conic (Column 1) at the point of contact $(−1,1),$then which of the following options is the only CORRECT combination for obtaining its equation?(I) (ii) (Q) (b) (III) (i) (P)(II) (ii) (Q) (d) $(I)(i)(P)$

Let $z_{k}=cos(2k10π )+isin(2k10π );k=1,2,34,…,9$ (A) For each $z_{k}$ there exists a $z_{j}$ such that $z_{k}.z_{j}=1$ (ii) there exists a $k∈{1,2,3,…,9}$ such that $z_{1}z=z_{k}$

Let $[x]$ be the greatest integer less than or equal to $x˙$ Then, at which of the following point (s) function $f(x)=xcos(π(x+[x]))$ is discontinuous? (a)$x=1$ (b) $x=−1$ (c) $x=0$ (d) $x=2$

From a point $P(λ,λ,λ)$, perpendicular PQ and PR are drawn respectively on the lines $y=x,z=1$ and $y=−x,z=−1$.If P is such that $∠QPR$ is a right angle, then the possible value(s) of $λ$ is/(are)