
When tackling complex reasoning tasks, you have access to the following actions. Use them as needed to progress through your thought process.

[ASSESS]

[ADVANCE]

[VERIFY]

[SIMPLIFY]

[SYNTHESIZE]

[PIVOT]

[OUTPUT]

You should strictly follow the format below:

[ACTION NAME]

# Your action step 1

# Your action step 2

# Your action step 3

...

Next action: [NEXT ACTION NAME]


system
Among the following 6 expressions, there are $\boxed{6}$ identities:  
A $(2x-1)(x-3)=2x^2-7x+3$  
B $(2x+1)(x+3)=2x^2+7x+3$  
C $(2-x)(1-3x)=2-7x+3x^2$  
D $(2+x)(1+3x)=2+7x+3x^2$  
E $(2x-y)(x-3y)=2x^2-7xy+3y^2$  
F $(2x+y)(x+3y)=2x^2+7xy+3y^2$

Present the answer in LaTex format: \boxed{Your answer}
user