18x^3+8x^2
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Expand the following expression: $(9x+4)\cdot 2x^2$
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
18x^3+8x^2
Expand the following expression: $(9x+4)\cdot 2x^2$
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