# Thread: Algebra 1 - Slope help

1. ## Algebra 1 - Slope help

Yea im back more help needed

Write an equation of the line shown in each graph, please explain how to do this one and i can understand the rest sorry its sideways i took the pic with my phone

2. You're looking for a line with the formula y= mx+ b , in which m= slope and b= y intercept.

First, use the slope formula with your two points to find the slope.
$\displaystyle \frac{y2-y1}{x2-x1}$
That is "m."

Next, plug one of your points, such as (-5,0) into the equation.

0= -5m + b
You should have m already from the slope formula. You then solve for b.

Finally, you put it all together.

y= mx+ b

Alternately, to find b you can use the formula y1-y= m(x-x1), called the point-slope formula.

4. Your two points are $\displaystyle (-5, 0)$ and $\displaystyle (0, 2)$.

You are looking for the equation of the line, i.e. $\displaystyle y = mx + c$ where m is the slope and c is the y-intercept.

We're given the y-intercept. It's 2.

So we just need the slope.

Here, $\displaystyle x_1 = -5, y_1 = 0, x_2 = 0, y_2 = 2$.

So using the slope of a line formula

$\displaystyle y = \frac{y_2 - y_1}{x_2 - x_1} = \frac{2 - 0}{0 - -5} = \frac{2}{5}$.

So the equation of the line is

$\displaystyle y = \frac{2}{5}x + 2$, or if you want to clean it up...

$\displaystyle 5y - 2x - 10 = 0$.