11 Choose the correct answer from those given : 11 If \( x^{2}-y^{2}=12, x+y=3 \), then \( x-y=\cdots \ldots \ldots \ldots . . . . . . . . . . . . . . . . . . . . ~ \)

To solve the equations \( x^{2} - y^{2} = 12 \) and \( x + y = 3 \), we can use the difference of squares formula. Remember that \( x^{2} - y^{2} = (x+y)(x-y) \). Given \( x + y = 3 \), we can substitute it into the first equation: \[ (x+y)(x-y) = 12 \implies 3(x-y) = 12 \] Now, divide both sides by 3: \[ x-y = \frac{12}{3} = 4 \] Thus, the answer is \( x-y = 4 \).