Find a non-zero value for $a$ such that $ax^2+8x+4=0$ has only one solution.
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Find a non-zero value for $a$ such that $ax^2+8x+4=0$ has only one solution.
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
4
Find a non-zero value for $a$ such that $ax^2+8x+4=0$ has only one solution.
train