Which symbol must all formula begin with? A. = B. + C. ( D. @

The correct answer is: A. =

A formula is an expression that uses mathematical symbols to represent a relationship between quantities. All formulas must begin with the equal sign (=). This is because the equal sign indicates that the expression on the left-hand side of the equation is equal to the expression on the right-hand side of the equation.

The other options are not correct because they are not mathematical symbols that are used to represent relationships between quantities. The plus sign (+) is used to add two quantities together. The parentheses () are used to group together quantities. The at sign (@) is not a mathematical symbol.