What is the sum of the two values which will make the following expression undefined? $$\frac{x-3}{2x^2-8x+7}$$
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
What is the sum of the two values which will make the following expression undefined? $$\frac{x-3}{2x^2-8x+7}$$
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
4
What is the sum of the two values which will make the following expression undefined? $$\frac{x-3}{2x^2-8x+7}$$
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