Question

The coefficients of x and y in the standard form of a linear equation cannot both be zero. Explain why.

Answer 1

The standard form of the equation of a line is
ax + by = c
If both a and b (the coefficients of x and y, respectively) are zero, then you have
0x + 0y = b
or 0 = b
which is the same as b = 0. This is simply a point on the number line, and it's not a line.