Answer
$mx+b$
(see Note below)
Work Step by Step
A linear equation is caller linear because its graph is a line.
Any equation of the form $y=mx+b$
is linear because its graph is a line.
We will write
$mx+b$
as the answer to this question, BUT:
Note:
There is a certain problem with the wording of this question.
Take the equation $x=4$.
Its graph is a (vertical) line, and CAN NOT be written in the form $y=mx+b$.
So, $y=mx+b$ does not cover all linear equations.
The answer we should write is
" we can not make the statement true",
because it should be true for "a linear equation", that is, for "all linear equations."
