factoring, developing, simplifying and solving
- Consider the expression `E=(10*x+9)^2-(10*x+9)*(4*x-5)`.
- Expand and reduce E.
- Factor E.
- Solve the equation `(7+3*x)*(9+10*x)=0`.
This type of exercise can be solved using the function : expand_and_simplify
Course reminder : Equations