MCQ
The general solution of the differntial equation $\frac{\text{dy}}{\text{dx}}=\frac{\text{y}}{\text{x}}$ is:
  • A
    $\log\text{y}=\text{kx}$
  • $\text{y}=\text{kx}$
  • C
    $\text{xy}=\text{k}$
  • D
    $\text{y}=\text{k}\log\text{x}$

Answer

Correct option: B.
$\text{y}=\text{kx}$
We have,
$\frac{\text{dy}}{\text{dx}}=\frac{\text{y}}{\text{x}}$
$\Rightarrow\frac{\text{1}}{\text{y}}\text{dy}=\frac{\text{1}}{\text{x}}\text{dx}$
Integrating both sides, we get
$\int\frac{\text{1}}{\text{y}}\text{dy}=\int\frac{\text{1}}{\text{x}}\text{dx}$
$\log\text{y}=\log\text{x}+\log\text{k}$
$\log\text{y}-\log\text{x}=\log\text{k}$
$\log\frac{\text{y}}{\text{x}}=\log\text{k}$
$\Rightarrow\frac{\text{y}}{\text{x}}=\text{k}$
$\Rightarrow\text{y}=\text{k}{\text{x}}$

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Similar questions

If $P(3, 2, -4), Q(5, 4, -6)$ and $R(9, 8, -10)$ are collinear, then $R$ divided $PQ$ in the ratio:
Consider the system of equations: $a_1x + b_1y + c_1z = 0 , a_2x + b_2y + c_2z = 0 , a_3x + b_3y + c_3z = 0,$
if$\begin{vmatrix}\text{a}_1&\text{b}_1&\text{c}_1\\\text{a}_2&\text{b}_2&\text{c}_2\\\text{a}_3&\text{b}_3&\text{c}_3\end{vmatrix}=0$, then the system has
The projection of any line on co-ordinate axes be respectively $3, 4, 5$ then its length is
Shortest distance between line $y - x = 1$ and curve  $x = {y^2}$ is 
The number of solutions of the system of equations : $2 x+y-z=7, x-3 y+2 z=1 , x+4 y-3 z=5$
Let $f$ be a real-valued function defined on the interval $(0, \infty)$ by $f(x)=\ln x+\int_0^x \sqrt{1+\sin t} d t$. Then which of the following statement(s) is (are) true?

$(A)$ $f^{\prime \prime}(x)$ exists for all $x \in(0, \infty)$

$(B)$ $f^{\prime}(x)$ exists for all $x \in(0, \infty)$ and $f^{\prime}$ is continuous on $(0, \infty)$, but not differentiable on $(0, \infty)$

$(C)$ there exists $\alpha>1$ such that $\left|f^{\prime}(x)\right|<|f(x)|$ for all $x \in(\alpha, \infty)$

$(D)$ there exists $\beta>0$ such that $|f(x)|+\left|f^{\prime}(x)\right| \leq \beta$ for all $x \in(0, \infty)$

Let $f: R \rightarrow R$ be a function defined by $f(x)=\left\{\begin{array}{cc}{[x],} & x \leq 2 \\ 0, & x>2\end{array}\right.$, where $[x]$ is the greatest integer less than or equal to $x$. If $I=\int_{-1}^2 \frac{x f\left(x^2\right)}{2+f(x+1)} d x$, then the value of $(4 I-1)$ is
The value of $\sum\limits_{n = 1}^N {{U_n},} $ if ${U_n} = \left| {\,\begin{array}{*{20}{c}}n&1&5\\{{n^2}}&{2N + 1}&{2N + 1}\\{{n^3}}&{3{N^2}}&{3N}\end{array}\,} \right|$ is
A coin is tossed $n$ times. The probability of geting at least once is greater than $0.8$. Then, the least value of $n,$ is :
If $A = [1, 2, 3],$ then the set of elements of $A$ is :