# How do you write an equation in slope intercept form given (2, 1) and has slope 3?

Feb 24, 2016

$y = 3 x - 5$

#### Explanation:

Standard format of the equation is $y = m x + c$

Where the slope is $m = 3$ giving:

$\text{ } y = 3 x + c$

We are told that the straight line graph passes through the point

$\text{ } \left(x , y\right) \to \left(2 , 1\right)$

So by substitution you end up with:

$\text{ "y=3x+c" becomes } 1 = 3 \left(2\right) + c$

$\text{ } 1 = 6 + c$

Subtract 6 from both sides giving

$\text{ } - 5 = c$

So the equation is

$\text{ } y = 3 x - 5$

Feb 24, 2016

y = 3x - 5

#### Explanation:

Begin by writing in the form : y - b = m(x - a) , the standard form for the equation of a straight line.
In this form . m = gradient(slope) and (a,b) , a point on the line.

here m = 3 and (a,b) = (2,1)

hence : y - 1 = 3(x - 2 ) → y - 1 = 3x - 6

in slope-intercept form y = 3x - 5