Question

(D-1)x + Dy = 0
(D+1)x + (2D+2)y = 0
How can i solve these equ. in MATLAB ?

Answer 1

by matrices

Answer 2

um, i'm only in high school, so i haven't read much about this type of equations, but from what i know, here's how i solved it, even if it's probably false:
1. let's start with : (D-1)x+ Dy = 0
according to it, we find D= (x)/(x+y)
2. now let's replace D in the second equation, it becomes like this:
(D+1)x+ (2D+2)y= 0
Dx + x + 2Dy + 2y= 0
D(x+2y) + x + 2y= 0
(x+ 2y) (D+1)= 0
(now we replace): (x+ 2y) ([x/(x+y)] + 1)= 0
(x+2y) ( [x(x+y)]/[x+y] )= 0
[x(x+y)(x+2y)]/(x+y)= 0
(x²+xy)(x+2y) =0
x^3 + 2x²y+ x²y+ 2xy² =0
x²+y(3x+2y) =0
x²+ 3xy+ 2y² =0
x²+ y²+ 2xy +xy + y² =0
(x+y)²+ y(x+y)=0
therefor: x=0 y=0
I don't know if 'im correst or not, i'm only 15 and i live in Africa!!