Which of the following is not an attribute of a linear equation?

the equation has a single variable.
the variable must be raised to the second power.
the equation is of the first degree.
the equation has an equal sign

The variable must be raised to second power but im not sure plz check it before you anwser

The first one, i believe, would be correct. all the others have one thing in common, and that's that they have repeating numbers. in the second one, x and y have repeating 6's and 3's, and in the third, x and y have repeating 6's as well. in the last one, there are repeating 3's. the first one has no repeating numbers.