The correct options are
A x2−3
D x2−5x+6
An algebraic expression consists of variables, constants and operators (+, -, /, x).
When an algebraic expression is equated to another algebraic expression or zero, it becomes an algebraic equation.
Hence, x2−3 and x2−5x+6 are algebraic expressions whereas, a=4 and 4x+7=6 are algebraic equations.