If you are looking for a Graphic Calculator to help with homework, the Desmos Graphing calculator is the best one to use that I have found.
To challenge yourself to a higher level in Algebra you need more challenging problems. Interactive Maths has a problem generator with levels so you can create the challenge and see the answer after you tried it.
As far as Scientific Calculators that also do matrices and solves, the Web2.0Calc is what I recommend.
Also, sometimes you want to view a PowerPoint as it was made, with animations to help understand the process, but you don’t own the very expensive software. You can download, for free, the viewer so you can watch the pptx’s on your own computer. It can be found here.