$\text{if a,b,c are in A.P and }\left(a+2b-c\right)\left(4b+2c-2a\right)\left(c+a-b\right)=\lambda \text{abc,then the value of} \lambda \text{ is}$

$$\begin{gathered} Consider the expression\left(a+2b-c\right)\left(4b+2c-2a\right)\left(c+a-b\right) \\ \sin ce a,b,c are in AP \\ 2b=a+c \\ \left(a+a+c-c\right)\left(2a+2c+2c-2a\right)\left(2b-b\right)=2a·4c·b=8abc \end{gathered}$$

$\text{hence λ=8}$