Ahhhhhhhh! Point slope form problems! Please help!?

Question

I have a test on these tomorrow, and I'm almost totally lost... Pleast help me with these problems:
Find the midpoint of BD B=(-5, 12) D=(-8,5)
Write th eequation of th eline through C and D in A) point-slope form B) slope-intercept form

Answer 1

point slope is:
#=y sub-one
@= x sub-one
m=slope

point slope form:
y-#=m(x-@)

point slope:
y=mx+b

m=slope
b= y intercept


HOPE THAT HELPS

Answer 2

the midpoint formula is x = (x + x1)/2 and y= (y + y1)/2
therefore x=(-5 + -8)/2 = -13/2 and y =(12 + 5)/2 =17/2
midpoint C=(-13/2 , 17/2)

Equation of line through C and D
point slope form is y - y1 = m (x - x1)

first we need m the slope
slope (m) = (y-y1)/ (x- x1)
= (17/2 - 5) / (-13/2 - (-8))
= (7/2)/(3/2) = 7/3

therefore we have y-5= 7/3(x+8)...*

slope intercept y = mx + c
from above equation..........*
y=(7/3)x+56/3 +5
y = 7/3 x +71/3

Answer 3

well, since you want to be sure you understand things for the test, I will work a different problem like this one, and then you can try yours.

B= ( 3, -6 ) D= ( -1,4)

midpoint: average of the x-coordinates is (3 + -1)/2 = 1
average of the y-coordinates = ( -6 +4)/2 = -1

so the midpoint is (1, -1)