How do you write an equation of a line parallel to y=3 passing through P(-2,4)?

Jun 19, 2015

$y = 4$

Explanation:

Your line, $y = 3$ is a horizontal line passing through $3$ (on the y axis). A line parallel to this one has to be again horizontal but this time passing through $4$, i.e. $y = 4$.

A somewhat more rigorous approach would be to say that the slope $m$ of $y = 3$ is zero so using the relationship:
$y - {y}_{0} = m \left(x - {x}_{0}\right)$
you get:
$y - 4 = 0 \left(x + 2\right)$
$y = 4$