Question

Point P lies on the line with the equation y-4=3(x-2). If the x-coordinate of P is 4, what is the y-coordinate of P

Answer 1

Let's start by tidying up that equation and put it into slope-intercept form (y = mx + b); from there, we can plug in coordinates.

$y - 4 = 3(x-2)$

Let's use the distributive property on the right side:
$y - 4= 3x - 6$

Now add 4 to both sides
$(y - 4) + 4 = (3x - 6) + 4$

Which simplifies to:
$y = 3x - 2$

Since that's the equation of our line, now we can plug in coordinates and see what it churns out. 

We know that the x-coordinate of P = 4 so let's substitute 4 in for x and calculate the y-coordinate:

$y = 3(4) - 2$
$y = 12 - 2$
$y = 10$

So the y-coordinate for point P = 10