MCQ
Let $\vec \alpha =(\lambda -2) \vec a + \vec b$ and $\vec \beta = (4\lambda -2)\vec a + 3\vec b$ be two given vectors where $\vec a$ and $\vec b$ are non collinear. The value of $\lambda $ for which vectors and $\vec \alpha $ and $\vec \beta $ are collinear, is
  • $-4$
  • B
    $-3$
  • C
    $4$
  • D
    $3$

Answer

Correct option: A.
$-4$
a
$\vec \alpha  = (\lambda  - 2)\overrightarrow {\rm{a}}  + \overrightarrow {\rm{b}} $

$\vec{\beta}=(4 \lambda-2) \overrightarrow{\mathrm{a}}+3 \overrightarrow{\mathrm{b}}$

$\bar{\alpha}$ and $\bar{\beta}$ are collinear

$\left|\begin{array}{cc}{\lambda-2} & {1} \\ {4 \lambda-2} & {3}\end{array}\right|=0$

$3 \lambda-6-4 \lambda+2=0$

$-\lambda-4=0$

$\lambda=-4$

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Similar questions

Consider the functions defined implicitly by the equation $y^3-3 y+x=0$ on various intervals in the real line. If $x \in(-\infty,-2) \cup(2, \infty)$, the equation implicitly defines a unique real valued differentiable function $y=f(x)$. If $x \in(-2,2)$, the equation implicitly defines a unique real valued differentiable function $y=g(x)$ satisfying $g(0)=0$.

$1.$  If $\mathrm{f}(-10 \sqrt{2})=2 \sqrt{2}$, then $\mathrm{f}^{\prime \prime}(-10 \sqrt{2})=$

$(A)$ $\frac{4 \sqrt{2}}{7^3 3^2}$ $(B)$ $-\frac{4 \sqrt{2}}{7^3 3^2}$ $(C)$ $\frac{4 \sqrt{2}}{7^3 3}$ $(D)$ $-\frac{4 \sqrt{2}}{7^3 3}$

$2.$ The area of the region bounded by the curves $y=f(x)$, the $x$-axis, and the lines $x=a$ and $x=b$, where $-\infty < \mathrm{a} < \mathrm{b} < -2$, is

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$(D)$ $-\int_a^b \frac{x}{3\left((f(x))^2-1\right)} d x-b f(b)+a f(a)$

$3.$ $\int_{-1}^1 g^{\prime}(x) d x=$

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