Question

Which is the equation in slope-intercept form for the line that passes through (3,3) and is parallel to x + 3y = 4?

Answer 1

Hi there! The first answer is correct.

Let's first set up the equation in general form
ax + by = c

The line is parallel to x + 3y = 4, and therefore the formula is x + 3y = c.

The line passes through the point (3, 3) so we can plug in those values into the formula.

3 + 3 × 3 = c
3 + 9 = c
12 = c
c = 12

Now we have found the equation of our formula:
x + 3y = 12

Rewrite the formula.
First subtract x from both sides.
3y = -x + 12

Divide both sides by 3.
y = -1/3x + 4

Therefore, the first answer is correct.

Answer 2

$k:x+3y=4\ \ \ |-x\\\\3y=-x+4\ \ \ |:3\\\\y=-\dfrac{1}{3}x+\dfrac{4}{3}\\\\l:y=mx+b\\\\l\ ||\ k\iff m=-\dfrac{1}{3}\\\\\text{therefore correct answer is}\ y=-\dfrac{1}{3}x+4$