# How do you write an equation in slope intercept form given m=1/3, and contains (-3,-15)?

-14 .Check below

#### Explanation:

Use the equation
$y - {y}_{1} = m \left(x - {x}_{1}\right)$

Where,

${y}_{1} = - 15$
${x}_{1} = - 3$
$m = \frac{1}{3}$

Next the equation is :
$y + 15 = \frac{1}{3} \left(x + 3\right)$
$3 y + 45 = x + 3$
Thus,
$y = \frac{x - 42}{3}$
or u can write
$y = \frac{1}{3} x - 14$

Now u can use the equation of straight line which is
$Y = m X + c$

compare the above equation with your result and the y-intercept is -14

Apr 3, 2018

$y = \frac{1}{3} x - 14$

#### Explanation:

$m$ is the slope/gradient of the line

$y = m x + c$ is the general equation of the straight line

So we know $y = \frac{1}{3} x + c$ and to find the value of $c$ we substitute the numbers in the coordinate that the line passes through

$y = \frac{1}{3} x + c$ (-3,-15)

$- 15 = \frac{1}{3}$$\times$$- 3 + c$

$- 15 = - 1 + c$

$c = - 14$

So the equation is $y = \frac{1}{3} x - 14$