Momentum

https://d2l.ai/chapter_optimization/momentum.html

Hi,
is there a small typo in the gradient computation following 11.6.7?
∂xf(x)=Q(x−Q−1c)
if we expand this, it will come to Qx - c which does not match the derivative of 11.6.6.
I think what is meant on the RHS is Q(x-x*)
Thanks,
krishnan