I have a question on the leaq instruction in Intel x86-64 assembly. My question is what is the 8 doing in the first instruction? I understand that leaq does not overwrite memory but allows you to basically build functions since it does not overwrite previous values. I see that on line two, we have x + 4y which makes sense, but what is the 8 doing that seems to not get used?

1. leaq 7(%rax, %rax,8),%rdx = 7 + 9x

2. leaq (%rax, %rcx,4), %rdx = x + 4y