Does khan academy cover all of algebra 2?

That is a good question, one that I think should be clarified and made clearly visible. As far as I'm concerned, the Khan Academy course has everything integral to an Algebra 2 course, so you should be able to find nearly everything you need. Some skills may reside in other courses due to textbook content and standard variances. https://www.khanacademy.org/math/algebra2

The following skills are what I've seen as Algebra 2 requirements, and that KA has:

• Equations and inequalities
• How to graph functions and linear equations
• How to solve systems of linear equations
• Matrices
• Polynomials and radical expressions
• Quadratic functions and inequalities
• Conic Sections
• Polynomial functions
• Rational expressions
• Exponential and logarithmic functions
• Sequences and series
• Discrete mathematics and probability
• Trigonometry

Depending on what resources or textbook you refer to, there will be slight variances in the content range of an Algebra 2 course. I believe the Khan Academy course has everything, with the Trigonometry and Statistics & Probability skills placed in their own sections, and Matrices in the Pre-calculus course. If you ever need to find a skill, give it a quick search on KA and you should be able to find it with ease.

In my experience, Khan Academy will usually have everything you need, sometimes requiring some quick searches. Of course, if you have any trouble, feel free to leave another question and we'll try to help as best as we can. You can learn anything (and solve anything!).

Hopefully this was useful!