Yvonne has four trophies: one for basketball, one for soccer, one for tennis,
and one for volleyball. but she can display only three of them at a time in her
trophy case. which list shows all possible combinations of three different
trophies?
o a. bst, bsv, vts
o b. bst, bsv, btv, stv
o c. bst, bsv, bts, bvs stv, svt
o d. vst, vtb, stv, bst

B. BST, BSV, BTV, STV

Step-by-step explanation:

The answer is B. BST, BSV, BTV, STV

Any other combination of three trophies will be a copy of one of the 4 above.

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