Solve: 6x + 3y = 7xy and 3x + 9y = 11xy.
The given equations are 6x + 3y = 7xy and 3x + 9y = 11xy.
Dividing by xy on both sides of the given equations, we get
Then,
… (1)
… (2)
If we substitute and in (1) and (2), we get
3p + 6q = 7 … (3)
9p + 3q = 11 … (4)
Now by elimination method,
Step 1: Multiply equation (3) by 3 and equation (4) by 1 to make the coefficients of x equal.
Then, we get the equations as:
9p + 18q = 21 … (5)
9p + 3q = 11 … (6)
Step 2: Subtract equation (6) from equation (5),
(9p – 9p) + (3q – 18q) = 11 – 21
⇒ - 15q = - 10
⇒
Step 3: Substitute q value in (3),
3p = 3
⇒ p = 1
We know that and .
Substituting values of p and q, we get
x = 1 and y =
The solution is x = 1 and y = .