Solve y 10y 21y 40y 100y 0 given that y xe5x is a solut
Solve y\'\'\'\' 10y\'\'\' + 21y\'\' + 40y\' 100y = 0 , given that y = xe^(5x) is a solution.
Solution
Given that
y\'\'\'\' 10y\'\'\' + 21y\'\' + 40y\' 100y = 0
then the characteristic equation is r4 - 10r3 + 21r2 + 40r - 100 = 0
Therefore the roots are r = - 2 , 2 , 5 , 5
Then the genaral solution is
y( x ) = C1 e-2x + C2 e2x + C3 e5x + C4 xe-5x
Where C1, C2 ,C3 , and C4 are arbitrary constants
