We were given an assignment to find a formula for finding the density of water. I wasn't in class when the assignment was given, but the teacher gave the class two values:

density H2O at 20 degrees C= .998823 g/mL
density H2O at 25 degrees C= .99707 g/mL

A friend of mine told me that the class was told to find the slope of this, when x= density and y= temperature. Then, we were to take this function, which is linear, and put it into y= mx + b form.

I know that the calculation for slope is
m= (y2-y1)/(x2-x1)

So, if my points were:
Pt1= 20.0, .998823
Pt2= 25.0, .99707

then my slope would be
-.00175/5.00 or -3.50 E-4

Is it possible to have a negative slope?
I know this equals m, so my equation right now would look like this:
y= -3.50E-4(x) + b
How do I find b??

Look at the two points. As T goes up, density goes down. That will give you the negative slope. To find b, set x = 0

That won't work, will it? If you are graphing the line, b is the y intercept.

To find the value of b, which represents the y-intercept of your linear equation, you need to substitute one of the given data points into the equation and solve for b.

Let's take one of the points you have, Pt1: (20.0, .998823)
Since the x-value represents temperature and the y-value represents density, we can substitute these values into the equation: y = -3.50E-4(x) + b.

So, plugging in the x-value (20.0) and the y-value (.998823), we get:
0.998823 = -3.50E-4(20.0) + b

Now, we can solve for b. Start by multiplying -3.50E-4 and 20.0:
-3.5E-4(20.0) = -7.00E-3

Now, let's rearrange the equation to solve for b:
0.998823 = -7.00E-3 + b

To isolate b, we can add 7.00E-3 to both sides of the equation:
0.998823 + 7.00E-3 = b

Finally, calculate the sum:
b = 0.998823 + 7.00E-3

The result will give you the value of b, which represents the y-intercept in the linear equation.