Maths-
General
Easy

Question

The solution of the differential equation square root of a plus x end root fraction numerator d y over denominator d x end fraction plus x y equals 0 is

  1. y equals A e to the power of 2 divided by 3 left parenthesis 2 a minus x right parenthesis square root of x plus a end root end exponent    
  2. y equals A e to the power of negative 2 divided by 3 left parenthesis a minus x right parenthesis square root of x plus a end root end exponent    
  3. y equals A e to the power of 2 divided by 3 left parenthesis 2 a plus x right parenthesis square root of x plus a end root end exponent    
  4. y equals A e to the power of negative 2 divided by 3 left parenthesis 2 a minus x right parenthesis square root of x plus a end root end exponent    

hintHint:

Use the separation of variables technique to solve the equation.

The correct answer is: y equals A e to the power of 2 divided by 3 left parenthesis 2 a minus x right parenthesis square root of x plus a end root end exponent


    square root of a plus x end root space fraction numerator d y over denominator d x end fraction space plus space x y space equals space 0
square root of a plus x end root space fraction numerator d y over denominator d x end fraction space equals space minus x y
square root of a plus x end root space d y space equals space minus x y space d x
fraction numerator d y over denominator y end fraction space equals space fraction numerator negative x over denominator square root of a plus x end root space end fraction space d x
I n t e g r a t i n g space b o t h space t h e space s i d e s comma
integral fraction numerator d y over denominator y end fraction space equals space integral fraction numerator negative x over denominator square root of a plus x end root space end fraction space d x
log y space equals space integral fraction numerator negative open parentheses x plus a minus a close parentheses over denominator square root of a plus x end root space end fraction space d x
log y space equals negative 1 space open parentheses integral fraction numerator open parentheses x plus a close parentheses over denominator square root of a plus x end root space end fraction space d x space minus space integral fraction numerator a over denominator square root of a plus x end root space end fraction space d x close parentheses
log y space equals space minus 1 open parentheses integral square root of x plus a end root space d x space minus a space integral fraction numerator 1 over denominator square root of a plus x end root space end fraction space d x close parentheses
log y space equals space minus 1 open parentheses 2 over 3 open parentheses x plus a close parentheses to the power of 3 over 2 end exponent space minus 2 a square root of x plus a end root close parentheses space plus space log A space space space space space space space space space space space space space space space open parentheses w h e r e space A space i s space a n space a r b i t r a r y space c o n s tan t close parentheses
log y space equals space space 2 a square root of x plus a end root space minus space 2 over 3 open parentheses x plus a close parentheses to the power of 3 over 2 end exponent space plus space log A
log y space equals space 2 square root of x plus a end root open parentheses a space minus space fraction numerator open parentheses x plus a close parentheses over denominator 3 end fraction close parentheses space plus space log A
log y space equals space 2 square root of x plus a end root open parentheses fraction numerator 3 a minus open parentheses x plus a close parentheses over denominator 3 end fraction close parentheses space plus space log A
log y space equals space 2 over 3 square root of x plus a end root open parentheses 3 a minus x minus a close parentheses space plus space log A
log y space equals 2 over 3 square root of x plus a end root open parentheses 2 a minus x close parentheses space plus space log A
y space equals space e to the power of 2 over 3 open parentheses 2 a minus x close parentheses square root of x plus a end root end exponent space space plus space e to the power of log A end exponent
therefore y space equals space A e to the power of 2 over 3 open parentheses 2 a minus x close parentheses square root of x plus a end root end exponent

    A differential equation is an equation which contains one or more terms and the derivatives of one variable (i.e., dependent variable) with respect to the other variable (i.e., independent variable) dy/dx = f(x)

    card img

    With Turito Academy.

    card img

    With Turito Foundation.

    card img

    Get an Expert Advice From Turito.

    Turito Academy

    card img

    With Turito Academy.

    Test Prep

    card img

    With Turito Foundation.