522 Views

dy/dx=3y-7x+7/3x-7y-3 solve the following differential equations


sakuntalaampolu 8th Nov, 2020
Answer (1)
Shivam Kumar 8th Nov, 2020

Hello sakuntalaampolu,

Well, before I start solving it, I must admit it is going to be very lengthy as I am using bernoulli's homogeneous differential equation method:

Now, In first, if an equation is of form dy/dx = (ax + by + c)/(-bx+ay+f), then we should cross multiply and solve easily, But this is not the case here, So, put y = v + k, where v is variable and k is a constant, And put x = u + h, where u is variable and h is constant, and we get:

dy/dx = (3v-7u +3k-7h+7)/(3u-7v +3h-7k-3), now we know y = v + k => dy = dv and similarly du = dx So, dy/dx = dv/du and Now, lets make 3k-7h+7=0 and 3h-7k-3=0 because we want homogeneous equation and also k and h are constants while we will decide by solving above 2 equations having h and k , h=10/7 and k=1; Now we have dv/du = (3v-7u)/(3u-7v) Now, how do we solve homogeneous equation? => by putting v = ut where t is a variable, so dv/du = t + u.dt/du(you can also do dv/dt , No problem!) and we now get :

t + u.dt/du =  (3t-7)/(3-7t) => u.dt/du = 7(t^2 -1)/3-7t and rearranging we get:

((3-7t)/(7(t^2 -1))dt = du/u , Now Integrate both side, and you are going to get like : (-3/7 ln(t+1) -2/7 ln(t^2 -1) = ln u;( I hope you can solve it like 3-7t = (3-3t) -4t and rest you can do...)

And to get your answer, you have to put first t=v/u and then v = y-1(v = y-k and k=1) and u = x-10/7 and this can done by anyone,

And I am expecting you get the solution, Now Summarising:

first make homogenised equation by (using y=v+k and x=u+h) and after you get homogenised equation, always do like upper variable = t. lower variable like y = tx or v = ut and you can do the reverse also like u=vt, this will also give correct answer) and then you get a easily differentiable function to integrate and after integrating you should put the actual values or variables going in backward direction...

Good Luck!

Hope this helps, and feel free to ask any further query...

Related Questions

Amity University Noida B.Tech...
Apply
Among Top 30 National Universities for Engineering (NIRF 2024) | 30+ Specializations | AI Powered Learning & State-of-the-Art Facilities
Amrita University B.Tech 2026
Apply
Recognized as Institute of Eminence by Govt. of India | NAAC ‘A++’ Grade | Upto 75% Scholarships
Amity University, Noida | Law...
Apply
700+ Campus placements at top national and global law firms, corporates and judiciaries
Great Lakes Institute of Mana...
Apply
Admissions Open | Globally Recognized by AACSB (US) & AMBA (UK) | 17.8 LPA Avg. CTC for PGPM 2025
Manav Rachna University Law A...
Apply
Admissions open for B.A. LL.B. (Hons.), B.B.A. LL.B. (Hons.) and LL.B Program (3 Years) | School of Law, MRU ranked No. 1 in Law Schools of Excelle...
Nirma University Law Admissio...
Apply
Grade 'A+' accredited by NAAC | Ranked 33rd by NIRF 2025
View All Application Forms

Download the Careers360 App on your Android phone

Regular exam updates, QnA, Predictors, College Applications & E-books now on your Mobile

150M+ Students
30,000+ Colleges
500+ Exams
1500+ E-books