1. What does the letter i mean or stand for in mathematics

1. The letter i referes to the imaginary numbers in mathematics.
2.i.i=-1
3.i.i.i=-i
As
[tex]i=\sqrt[\square]{-1}[/tex]Thus multiplying i two times gives us -i.
4. The given equation:
[tex]2x^2-22=-7x[/tex]Rearranging,
[tex]2x^2+7x-22=0[/tex]Solving,
[tex]2x^2+11x-4x-22=0[/tex][tex](2x+11)(x-2)=0[/tex]Solving,
[tex]x=-\frac{11}{2},2[/tex]The siolution is x=-11/2,2