Math CentralQuandaries & Queries


Question from dana, a student:

I don't know what is 2xy what does that mean? is it 2x+2y or 2x times y
Please help! thank you for your time!! :)

Hi Dana,

The symbol $x$ stands for an unknown number, the symbol $y$ stands for an unknown number and the symbol 2 stands for a known number, two. In algebra when two symbols that stand for a number are placed beside each other the operation between them is taken to be multiplication. Thus $2xy$ means 2 times $x$ times $y$ or said algebraically $2xy = 2 \times x \times y.$ If you want the operation between two symbols to be something else, like plus, you have to say it explicitly. Thus for $x$ plus $y$ you need to write $x + y.$

I hope this helps,


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