
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
Given the quadratic function $f(x)= \frac {1}{4}x^{2}+1$, a line $l_{1}$ passes through the point $M(a,0)$, and $l_{2}$ is tangent to the graph of $f(x)$ at points $A$ and $B$. Determine the equation of the line $AB$.

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