Answer:
There are a few ways you can know that the equation of a line is wrong without performing calculations:
The equation does not have the correct form for a line. A line in the form "y = mx + b" is a slope-intercept form, where "m" is the slope of the line and "b" is the y-intercept (the point where the line crosses the y-axis). If the equation does not have this form, it is not an equation of a line.
The equation does not represent a straight line. If the equation is not linear (i.e. if it contains terms with exponents other than 1), it will not represent a straight line.
The graph of the equation does not look like a line. If you plot the equation on a graph and it does not look like a straight line, the equation is likely incorrect.
The equation does not pass through known points. If you have a set of points that are known to lie on the line, you can check if the equation passes through those points. If it does not, the equation is likely incorrect.