What is the coefficient of $x^2y^2$ in the expansion of $(x+y)^4+(x+2y)^4$?
Question:
What is the coefficient of $x^2y^2$ in the expansion of $(x+y)^4+(x+2y)^4$?
Answer:
Let's think step by step.

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What is the coefficient of $x^2y^2$ in the expansion of $(x+y)^4+(x+2y)^4$?
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