Solve for x and y:
4x + 6y = 3xy, 8x + 9y = 5xy (x ≠ 0, y ≠ 0)
We have
4x + 6y = 3xy
and 8x + 9y = 5xy
where x≠0 and y≠0
Lets simplify these equations.
4x + 6y = 3xy
Dividing the equation by xy throughout,
⇒
Assuming p = 1/y and q = 1/x, we get
4p + 6q = 3 …(i)
Also, 8x + 9y = 5xy
Dividing the equation by xy throughout,
⇒
Assuming p = 1/y and q = 1/x, we get
⇒ 8p + 9q = 5 …(ii)
To solve these equations, we need to make one of the variables (in both the equations) have same coefficient.
Lets multiply eq.(i) by 2, so that variable p in both the equations have same coefficient.
Recalling equations (i) & (ii),
4p + 6q = 3 [×2
8p + 9q = 5
⇒ 3q = 1
⇒ q = 1/3
Substitute q = 1/3 in eq.(i)/eq.(ii), as per convenience of solving.
Thus, substituting in eq.(i), we get
4p + 6(1/3) = 3
⇒ 4p + 2 = 3
⇒ 4p = 3 – 2 = 1
⇒ p = 1/4
Thus, p = 1/4 and q = 1/3
As q = 1/x,
⇒ 1/3 = 1/x
⇒ x = 3
And p = 1/y
⇒ 1/4 = 1/y
⇒ y = 4
Hence, we have x = 3 and y = 4