Wolfram: Typesetting Math

To typeset math formulas, simply type the expressions normally, then press Ctrl+Shift+n

HoldForm[ (-b + Sqrt[b^2 - 4 a c] ) / (2 a) ]

HoldForm @ Sum[ (-1)^n/(2*n + 1), {n, 0, ∞}]

Table[ (-1)^n/(2*n + 1), {n, 0, 4}]
(* {1, -1/3, 1/5, -1/7, 1/9} *)

HoldForm @ Integrate[ f[x] , {x,a,b}]

HoldForm @ Limit[ (f[a+h]-f[a])/h, {h -> 0}]

HoldForm @ MatrixForm @ {{1,2},{3,4}}

• Parenthesis () is used for one thing only: group expressions.
• Square brackets [] is used for one thing only: arguments for functions.
• Curly brackets {} is used for one thing only: a list of things (for set, or vector, or nested for matrix, tensor).

HoldForm

for some expression, you might wrap HoldForm[] around it, to prevent it from eval. For example, Sum[1/n, {n,1,4}] gets evaluated to a fraction. But HoldForm @ Sum[1/n, {n,1,4}] hold it as typeset expression.