Algebra PYQ — Page 38

Let ${{{a}_{n}}}_{n=0}^{\infty }$ be a sequence such that ${a}_{0}={a}_{1}=0$ and ${a}_{n+2}=2{a}_{n+1}-{a}_{n}+1$ for all $n\geq 0$. Then, $\sum _{n=2}^{\infty }\frac{{a}_{n}}{{7}^{n}}$ is equal to

Let $A={1,{a}_{1},{a}_{2}\ldots \ldots {a}_{18},77}$ be a set of integers with $1<{a}_{1}<{a}_{2}<\ldots ..<{a}_{18}<77$. Let the set $A+A={x+y:x,y\in A}$ contain exactly $39$ elements. Then, the value of ${a}_{1}+{a}_{2}+\ldots ..+{a}_{18}$ is equal to ______.

Let${A}_{1},{A}_{2},{A}_{3},\ldots \ldots$ be an increasing geometric progression of positive real numbers. If ${A}_{1}{A}_{3}{A}_{5}{A}_{7}=\frac{1}{1296}$ and ${A}_{2}+{A}_{4}=\frac{7}{36}$, then, the value of ${A}_{6}+{A}_{8}+{A}_{10}$ is equal to

If $\frac{1}{2\cdot {3}^{10}}+\frac{1}{{2}^{2}\cdot {3}^{9}}+\ldots +\frac{1}{{2}^{10}\cdot 3}=\frac{K}{{2}^{10}\cdot {3}^{10}}$, then the remainder when $K$ is divided by $6$ is

The remainder when ${(2021)}^{2023}$ is divided by $7$ is

Let $S={(\begin{matrix}-1 & a \\ 0 & b\end{matrix});a,b\in {1,2,3,\ldots 100}}$ and let ${T}_{n}={A\in S:{A}^{n(n+1)}=I}$. Then the number of elements in $\cap _{n=1}^{100}{T}_{n}$ is _____.

Consider the sequence ${a}_{1},{a}_{2},{a}_{3},\ldots \ldots$ such that ${a}_{1}=1,{a}_{2}=2$ and ${a}_{n+2}=\frac{2}{{a}_{n+1}}+{a}_{n}$ for $n=1,2,3,\ldots$ If $(\frac{{a}_{1}+\frac{1}{{a}_{2}}}{{a}_{3}})\cdot (\frac{{a}_{2}+\frac{1}{{a}_{3}}}{{a}_{4}})\cdot (\frac{{a}_{3}+\frac{1}{{a}_{4}}}{{a}_{5}})\ldots (\frac{{a}_{30}+\frac{1}{{a}_{31}}}{{a}_{32}})={2}^{\alpha }(C3161)$ then $\alpha$ is equal to

If $1+(2+C149+C249+\ldots .+C4949)(C250+C450+\ldots ..+C5050)$ is equal to ${2}^{n}.m$, where $m$ is odd, then $n+m$ is equal to _____ .

Let $A={x\in R:|x+1|<2}$ and $B={x\in R:|x-1|\geq 2}$. Then which one the following statements is NOT true?

Let for $n=1,2,\ldots \ldots ,50,{S}_{n}$ be the sum of the infinite geometric progression whose first term is ${n}^{2}$ and whose common ratio is $\frac{1}{{(n+1)}^{2}}$. Then the value of $\frac{1}{26}+\sum _{n=1}^{50}({S}_{n}+\frac{2}{n+1}-n-1)$ is equal to

The probability that a randomly chosen one-one function from the set ${a,b,c,d}$ to the set ${1,2,3,4,5}$ satisfied $f(a)+2f(b)-f(c)=f(d)$ is

Let $A$ be a matrix of order $2\times 2$, whose entries are from the set ${0,1,2,3,4,5}$. If the sum of all the entries of $A$ is a prime number $p,2<p<8$, then the number of such matrices $A$ is

Let $A=(\begin{matrix}2 & -2 \\ 1 & -1\end{matrix})$ and$B=(\begin{matrix}-1 & 2 \\ -1 & 2\end{matrix})$ . Then the number of elements in the set {$(n,m):n,m\in {1,2,\ldots \ldots .10}$ and $n{A}^{n}+m{B}^{m}=I$} is _____.

The number of matrices $A=[\begin{matrix}a & b \\ c & d\end{matrix}]$, where $a,b,c,d\in {-1,0,1,2,3,\ldots \ldots ,10}$, such that $A={A}^{-1}$, is ______.

Let $A=[\begin{matrix}1 & a & a \\ 0 & 1 & b \\ 0 & 0 & 1\end{matrix}],a,b\in \mathbb{R}$. If for some $n\in N,{A}^{n}=[\begin{matrix}1 & 48 & 2160 \\ 0 & 1 & 96 \\ 0 & 0 & 1\end{matrix}]$ then $n+a+b$ is equal to _______.

Let $A=(\begin{matrix}4 & -2 \\ \alpha & \beta \end{matrix})$. If ${A}^{2}+\gamma A+18I=O$, then $det(A)$ is equal to _______.

Which of the following matrices can NOT be obtained from the matrix $[\begin{matrix}-1 & 2 \\ 1 & -1\end{matrix}]$ by a single elementary row operation?

Let a set $A={A}_{1}\cup {A}_{2}\cup \ldots \cup {A}_{k}$, where ${A}_{i}\cap {A}_{j}=\phi$ for $i\neq j;1\leq i,j\leq k.$ Define the relation $R$ from $A$ to $A$ by $R=${$(x,y):y\in {A}_{i}$ if and only if $x\in {A}_{i},1\leq i\leq k$}. Then, $R$ is:

Let $X=[\begin{matrix}0 & 1 & 0 \\ 0 & 0 & 1 \\ 0 & 0 & 0\end{matrix}],Y=\alpha l+\beta X+\gamma {X}^{2}$ and $Z={\alpha }^{2}I-\alpha \beta X+({\beta }^{2}-\alpha \gamma ){X}^{2},\alpha ,\beta ,\gamma \in \mathbb{R}$. If ${Y}^{-1}=[\begin{matrix}\frac{1}{5} & \frac{-2}{5} & \frac{1}{5} \\ 0 & \frac{1}{5} & \frac{-2}{5} \\ 0 & 0 & \frac{1}{5}\end{matrix}]$, then ${(\alpha -\beta +\gamma )}^{2}$ is equal to ______.

Let $S={1,2,3,4,5,6,7,8,9,10}$. Define $f:S\rightarrow S$ as $f(n)={\begin{matrix}2n, & \mathrm{if}n=1,2,3,4,5 \\ 2n-11 & \mathrm{if}n=6,7,8,9,10\end{matrix}$ Let $g:S\geq S$ be a function such that $\mathrm{fog}(n)={\begin{matrix}n+1 & ,\mathrm{if}n\mathrm{is}\mathrm{odd} \\ n-1 & ,\mathrm{if}n\text{is }\mathrm{even}\end{matrix}$, then $g(10)(g(1)+g(2)+g(3)+g(4)+g(5))$ is equal to

Let $S=${$\sqrt{n}:1\leqslant n\leqslant 50$ and $n$ is odd}. Let $a\in S$ and $A=[\begin{matrix}1 & 0 & a \\ -1 & 1 & 0 \\ -a & 0 & 1\end{matrix}]$. If $\underset{a\in S}{\Sigma }det(adjA)=100\lambda$, then $\lambda$ is equal to

Let the matrix $A=[\begin{matrix}0 & 1 & 0 \\ 1 & 0 & 0 \\ 0 & 0 & 1\end{matrix}]$ and the matrix ${B}_{0}={A}^{49}+2{A}^{98}$. If ${B}_{n}=\mathrm{Adj}({B}_{n-1})$ for all $n\geq 1$, then $det({B}_{4})$ is equal to

Let $A=[\begin{matrix}2 & -1 & -1 \\ 1 & 0 & -1 \\ 1 & -1 & 0\end{matrix}]$ and $B=A-I$. If $\omega =\frac{\sqrt{3}i-1}{2}$, then the number of elements in the set ${n\in {1,2,\ldots ,100}:{A}^{n}+{(\omega B)}^{n}=A+B}$ is equal to _____ .

Let $a,b$ be two non-zero real numbers. If $p$ and $r$ are the roots of the equation ${x}^{2}-8ax+2a=0$ and $q$ and $s$ are the roots of the equation ${x}^{2}+12bx+6b=0$, such that $\frac{1}{p},\frac{1}{q},\frac{1}{r},\frac{1}{s}$ are in A.P., then ${a}^{-1}-{b}^{-1}$ is equal to _____ .