
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 that $i$ and $j$ are unit vectors, and their directions are the same as the positive directions of the $x$-axis and $y$-axis, respectively, let $a=i-2j$ and $b=i+λj$, where the angle between $a$ and $b$ is acute. Determine the range of values for the real number $λ$.

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