Linear System and Inverse Existence

Questions about solving linear systems, proving existence/uniqueness of solutions, computing or proving properties of matrix inverses.

jee-main 2020 Q59 View
If $A = \begin{pmatrix} 2 & 2 \\ 9 & 4 \end{pmatrix}$ and $I = \begin{pmatrix} 1 & 0 \\ 0 & 1 \end{pmatrix}$, then $10A^{-1}$ is equal to.
(1) $A - 4I$
(2) $6I - A$
(3) $A - 6I$
(4) $4I - A$
jee-main 2020 Q61 View
Let $S$ be the set of all $\lambda \in R$ for which the system of linear equations $$2x - y + 2z = 2$$ $$x - 2y + \lambda z = -4$$ $$x + \lambda y + z = 4$$ has no solution. Then the set $S$
(1) Contains more than two elements
(2) Is an empty set
(3) Is a singleton
(4) Contains exactly two elements
jee-main 2020 Q62 View
Let $A = \left\{ X = ( x , y , z ) ^ { T } : P X = 0 \text{ and } x ^ { 2 } + y ^ { 2 } + z ^ { 2 } = 1 \right\}$ where $P = \left[ \begin{array} { c c c } 1 & 2 & 1 \\ - 2 & 3 & - 4 \\ 1 & 9 & - 1 \end{array} \right]$ then the set $A$
(1) Is a singleton.
(2) Is an empty set.
(3) Contains more than two elements
(4) Contains exactly two elements
jee-main 2020 Q61 View
If the system of equations $x + y + z = 2$ $2 x + 4 y - z = 6$ $3 x + 2 y + \lambda z = \mu$ has infinitely many solutions, then:
(1) $\lambda + 2 \mu = 14$
(2) $2 \lambda - \mu = 5$
(3) $\lambda - 2 \mu = - 5$
(4) $2 \lambda + \mu = 14$
jee-main 2020 Q62 View
If the system of linear equations $$x + y + 3z = 0$$ $$x + 3y + k^2z = 0$$ $$3x + y + 3z = 0$$ has a non-zero solution $(x, y, z)$ for some $k \in \mathrm{R}$, then $x + \left(\frac{y}{z}\right)$ is equal to:
(1) $-3$
(2) $9$
(3) $3$
(4) $-9$
jee-main 2020 Q62 View
The values of $\lambda$ and $\mu$ for which the system of linear equations $x + y + z = 2 , x + 2 y + 3 z = 5$, $x + 3 y + \lambda z = \mu$ has infinitely many solutions, are respectively
(1) 6 and 8
(2) 5 and 7
(3) 5 and 8
(4) 4 and 9
jee-main 2021 Q67 View
For the system of linear equations: $$x - 2 y = 1 , x - y + k z = - 2 , k y + 4 z = 6 , k \in R$$ Consider the following statements:
(A) The system has unique solution if $k \neq 2 , k \neq - 2$.
(B) The system has unique solution if $k = - 2$.
(C) The system has unique solution if $k = 2$.
(D) The system has no-solution if $k = 2$.
(E) The system has infinitely many solutions if $k = - 2$.
jee-main 2021 Q69 View
The system of linear equations $3 x - 2 y - k z = 10$ $2 x - 4 y - 2 z = 6$ $x + 2 y - z = 5 m$ is inconsistent if:
(1) $k = 3 , \quad m \neq \frac { 4 } { 5 }$
(2) $k = 3 , \quad m = \frac { 4 } { 5 }$
(3) $k \neq 3 , \quad m \in R$
(4) $k \neq 3 , \quad m \neq \frac { 4 } { 5 }$
jee-main 2021 Q68 View
Consider the following system of equations: $$\begin{aligned} & x + 2 y - 3 z = a \\ & 2 x + 6 y - 11 z = b \\ & x - 2 y + 7 z = c \end{aligned}$$ where $a , b$ and $c$ are real constants. Then the system of equations :
(1) has a unique solution when $5 a = 2 b + c$
(2) has no solution for all $a , b$ and $c$
(3) has infinite number of solutions when $5 a = 2 b + c$
(4) has a unique solution for all $a , b$ and $c$
jee-main 2021 Q72 View
The system of equations $kx + y + z = 1$, $x + ky + z = k$ and $x + y + zk = k^2$ has no solution if $k$ is equal to:
(1) 0
(2) 1
(3) $-1$
(4) $-2$
jee-main 2021 Q69 View
The value of $k \in R$, for which the following system of linear equations $3 x - y + 4 z = 3$ $x + 2 y - 3 z = - 2$ $6 x + 5 y + k z = - 3$ has infinitely many solutions, is:
(1) 3
(2) - 5
(3) 5
(4) - 3
jee-main 2022 Q68 View
Let the system of linear equations $x + y + a z = 2$ $3 x + y + z = 4$ $x + 2 z = 1$ have a unique solution $\left( x ^ { * } , y ^ { * } , z ^ { * } \right)$. If $\left( \left( a , x ^ { * } \right) , \left( y ^ { * } , \alpha \right) \right.$ and $\left( x ^ { * } , - y ^ { * } \right)$ are collinear points, then the sum of absolute values of all possible values of $\alpha$ is:
(1) 4
(2) 3
(3) 2
(4) 1
jee-main 2022 Q70 View
The number of values of $\alpha$ for which the system of equations $x + y + z = \alpha$ $\alpha x + 2 \alpha y + 3 z = - 1$ $x + 3 \alpha y + 5 z = 4$ is inconsistent, is
(1) 0
(2) 1
(3) 2
(4) 3
jee-main 2022 Q70 View
Let $A$ be a $3 \times 3$ real matrix such that $A \begin{pmatrix} 1 \\ 1 \\ 0 \end{pmatrix} = \begin{pmatrix} 1 \\ 1 \\ 0 \end{pmatrix}$; $A \begin{pmatrix} 0 \\ 0 \\ 1 \end{pmatrix} = \begin{pmatrix} 0 \\ 0 \\ 1 \end{pmatrix}$ and $A \begin{pmatrix} 1 \\ 0 \\ 1 \end{pmatrix} = \begin{pmatrix} 1 \\ 2 \\ 1 \end{pmatrix}$. If $X = \begin{pmatrix} x _ { 1 } \\ x _ { 2 } \\ x _ { 3 } \end{pmatrix}$ and $I$ is an identity matrix of order 3, then the system $( A - 2I ) X = \begin{pmatrix} 1 \\ 1 \\ 2 \end{pmatrix}$ has
(1) no solution
(2) infinitely many solutions
(3) unique solution
(4) exactly two solutions
jee-main 2022 Q69 View
If the system of equations $\alpha x + y + z = 5 , x + 2 y + 3 z = 4 , x + 3 y + 5 z = \beta$ has infinitely many solutions, then the ordered pair $( \alpha , \beta )$ is equal to
(1) $( 1 , - 3 )$
(2) $( - 1,3 )$
(3) $( 1,3 )$
(4) $( - 1 , - 3 )$
jee-main 2022 Q71 View
The system of equations $-kx + 3y - 14z = 25$ $-15x + 4y - kz = 3$ $-4x + y + 3z = 4$ is consistent for all $k$ in the set
(1) $R$
(2) $R - \{-11, 13\}$
(3) $R - \{-13\}$
(4) $R - \{-11, 11\}$
jee-main 2022 Q69 View
If the system of linear equations $2x + 3y - z = -2$ $x + y + z = 4$ $x - y + |\lambda|z = 4\lambda - 4$ where $\lambda \in \mathbb{R}$, has no solution, then
(1) $\lambda = 7$
(2) $\lambda = -7$
(3) $\lambda = 8$
(4) $\lambda^2 = 1$
jee-main 2022 Q72 View
If the system of linear equations $2 x + y - z = 7$ $x - 3 y + 2 z = 1$ $x + 4 y + \delta z = k$, where $\delta , k \in R$ has infinitely many solutions, then $\delta + k$ is equal to
(1) $- 3$
(2) 3
(3) 6
(4) 9
jee-main 2022 Q72 View
The number of real values of $\lambda$, such that the system of linear equations $2x - 3y + 5z = 9$ $x + 3y - z = -18$ $3x - y + (\lambda^2 - |\lambda|)z = 16$ has no solutions, is
(1) 0
(2) 1
(3) 2
(4) 4
jee-main 2022 Q70 View
If the system of equations $x + y + z = 6$ $2x + 5y + \alpha z = \beta$ $x + 2y + 3z = 14$ has infinitely many solutions, then $\alpha + \beta$ is equal to
(1) 8
(2) 36
(3) 44
(4) 48
jee-main 2023 Q69 View
Let $N$ denote the number that turns up when a fair die is rolled. If the probability that the system of equations $x + y + z = 1$, $2 x + N y + 2 z = 2$, $3 x + 3 y + N z = 3$ has unique solution is $\frac { k } { 6 }$, then the sum of value of $k$ and all possible values of $N$ is
(1) 18
(2) 19
(3) 20
(4) 21
jee-main 2023 Q77 View
If a point $P(\alpha, \beta, \gamma)$ satisfying $\begin{pmatrix} \alpha & \beta & \gamma \end{pmatrix} \begin{pmatrix} 2 & 10 & 8 \\ 9 & 3 & 8 \\ 8 & 4 & 8 \end{pmatrix} = \begin{pmatrix} 0 & 0 & 0 \end{pmatrix}$ lies on the plane $2x + 4y + 3z = 5$, then $6\alpha + 9\beta + 7\gamma$ is equal to $\_\_\_\_$.
jee-main 2023 Q77 View
For the system of equations $x + y + z = 6$ $x + 2y + \alpha z = 10$ $x + 3y + 5z = \beta$, which one of the following is NOT true?
(1) System has no solution for $\alpha = 3, \beta = 24$
(2) System has a unique solution for $\alpha = -3, \beta = 14$
(3) System has infinitely many solutions for $\alpha = 3, \beta = 14$
(4) System has a unique solution for $\alpha = 3, \beta = 14$
jee-main 2023 Q71 View
Let $S$ denote the set of all real values of $\lambda$ such that the system of equations $$\lambda x + y + z = 1$$ $$x + \lambda y + z = 1$$ $$x + y + \lambda z = 1$$ is inconsistent, then $\sum_{\lambda \in S} (\lambda^2 + \lambda)$ is equal to
(1) 2
(2) 12
(3) 4
(4) 6
jee-main 2023 Q77 View
Let A be a symmetric matrix such that $| A | = 2$ and $\left[ \begin{array} { l l } 2 & 1 \\ 3 & \frac { 3 } { 2 } \end{array} \right] A = \left[ \begin{array} { l l } 1 & 2 \\ \alpha & \beta \end{array} \right]$. If the sum of the diagonal elements of A is $s$, then $\frac { \beta s } { \alpha ^ { 2 } }$ is equal to $\_\_\_\_$.