Thread: have solution but i cannot understand

hi

y"+9 y = x^2
let yp= Ax^2 +Bx + c
y'=2Ax+B
y"=2A
thus giving you 2A+9(Ax^2 +Bx+C)=x^2
here where i am confused

Equate X^2 : 9A
thus A = 1/9
Equate x :B
9B=0
B=0

someone mind explaining it to me in layman term?
Thanks in advance

If and , then what's ?

2A+9Ax^2 +9Bx+9C=x^2

Originally Posted by salohcinseah

2A+9Ax^2 +9Bx+9C=x^2

Yes, now rewrite the LHS and RHS as

.


Does it make sense that and ?

yes it make more sense now thank you so much

Originally Posted by salohcinseah

hi

y"+9 y = x^2
let yp= Ax^2 +Bx + c
y'=2Ax+B
y"=2A
thus giving you 2A+9(Ax^2 +Bx+C)=x^2
here where i am confused

Equate X^2 : 9A
thus A = 1/9
Equate x :B
9B=0
B=0

someone mind explaining it to me in layman term?
Thanks in advance

I don't fully understand: the above is a differential equation so you must have some

track in mathematics already walked (at the very least some basic courses in calculus

and linear algebra), so how much layman terminology do you need?

Anyway, you've a polynomial identity , and we must

know that two pol's (whose coefficients are taken from the same field) are equal iff

coefficients of the corresponding same powers of x are equal, thus:

-- quadratic coefficient in both sides of the above equality must be the same,

-- the lineal coef. in both sides must be equal,

-- free coef's must be equal,

Tonio