Differential Equations — Class 12 Maths Solution

exemplar objective MCQ NCERT EXEMP.Q.36,Page.195
Question

The order and degree of the differential equation$\frac{{{d^2}y}}{{d{x^2}}} + {\left( {\frac{{dy}}{{dx}}} \right)^{1/4}} + {x^{1/5}} = 0$
respectively, are

  • (a) 2 and 4 ✓ Correct
  • (b) 2 and 2
  • (c) 2 and 3
  • (d) 3 and 3
Step-by-step Solution
Correct answer: option (a)

Given that, $\frac{{{d^2}y}}{{d{x^2}}} + {\left( {\frac{{dy}}{{dx}}} \right)^{1/4}} = - {x^{1/5}}$

$\Rightarrow$ $\frac{{{d^2}y}}{{d{x^2}}} + {\left( {\frac{{dy}}{{dx}}} \right)^{1/4}} = - {x^{1/5}}$

$\Rightarrow$ ${\left( {\frac{{dy}}{{dx}}} \right)^{1/4}} = - \left( {{x^{1/5}} + \frac{{{d^2}y}}{{d{x^2}}}} \right)$

On squaring both sides,

we get
${\left( {\frac{{dy}}{{dx}}} \right)^{1/2}} = {\left( {{x^{1/5}} + \frac{{{d^2}y}}{{d{x^2}}}} \right)^2}$

Again, on squaring both sides,

we have
$\frac{{dy}}{{dx}} = {\left( {{x^{1/5}} + \frac{{{d^2}y}}{{d{x^2}}}} \right)^4}$

order $= 2$, degree $= 4$

NCERT & Exemplar solution for CBSE Class 12 Mathematics, Differential Equations. Curated by Sachin Sharma. Free for all students.