Determinant and solution of equations

Question

Solve Question D3 of the image whose link is given below

https://i.stack.imgur.com/xS576.jpg My approach:
I made a matrix of all the coefficients say A (3*3) and then I made a column matrix of variables say X and equated the product of AX to column matrix B (4,3,3) Since the condition for infinite solution or no solution is |A|=0 If it has no solution then adjAB=!0 But this didn’t took me to the answer

Answer 1

Multiplying the second equation by $-1$ and adding to9 the first and doing the same with the last equation we get $$x+2y+3z=4$$ $$2y-py+z=1$$ $$-2y-\mu z+3z=1$$ Eliminating $z$ we get $$y(8-3p+\mu p-2\mu)=2+\mu$$ Infinity many solutions we get if $$\mu=-2$$ and $$p=2$$