The coefficient of the middle term in the binomial expansion of ${(1 + ax)}^4$ and of ${(1 – ax)}^6$ 6 is the same is $a$ equals

Middle term in the expansion of ${(1+ax)}^4$ is ${ }^4{C}_2(\alpha x{)}^2=6{\alpha }^2{x}^2$ 

and the middle term in the expansion of  $(1-\alpha x{)}^6$ is ${ }^6{C}_3(-\alpha x{)}^3=-20{\alpha }^3{x}^3$.
We are given $6{\alpha }^2=-20{\alpha }^3\Rightarrow \alpha =0$ or $\alpha =-\frac{3}{10}$