Question

write an equation for a diameter has end points (-10,1) and (-8,5)

Answer 1

The slope of this diameter (line) is 

        5 - 1
m = ------------ = 4/2 = 2
        -8-(-10)

Using the slope-intercept formula:

y = mx + b  =>  5  = (2)(-8) + b, or   5 + 16 = b = 21

Then the equation of the diameter (line) is y = 2x + 21.