You are an avid coin collector. You decide to start keeping better track of your coin collection:after 15 days you count and find out you have 155 coins. After 22 days, you have 218 coins. Write an equation in point-slope form

9514 1404 393

  y - 155 = 9(x -15)

Step-by-step explanation:

The given points are ...

  (days, coins) = (15, 155) and (22, 218)

The slope is given by the slope formula:

  m = (y2 -y1)/(x2 -x1) = (218 -155)/(22 -15) = 63/7 = 9

The point-slope form is for a line with slope m through point (h, k) is ...

  y -k = m(x -h)

Here, we have m=9 and (h, k) = (15, 155), so the equation can be written ...

  y - 155 = 9(x -15)

the value of v.w= -12.

step-by-step explanation:

we are given three vector r,v and w as:

r = < 5, -5, -2> ; v = < 2, -8, -8> ; w = < -2, 6, -5>

we know that r,v and w could also be represented as:

r=5i-5j-2k

v=2i-8j-8k

and w= -2i+6j-5k

where i,j and k are the unit vectors of x,y and z-axis respectively.

also we know that it has the following property:

i.i=1 ; j.j=1; k.k=1

and i.=j.i=i.k=k.i=j.k=k.j=0

i.e. when we multiply two vectors or we find it's dot product we need to only multiply the components of x coordinates with each other; y with each other and z with each other.

hence, v.w= (2i-8j- -2i+6j-5k)

                  = 2×(-2)+(-8)×(6)+(-8)×(-5)

                  = -4-48+40

                  = -12

hence, v.w= -12