In the sequence generated by the formula an=(-1)^n+1(5)^n, which of the following terms has the greatest value? Assume an > 0.
a. an
b. an+5
c. an+10
d. an+15

c a(n+10)

Step-by-step explanation:

[(-1)^(n+1)] × (5^n)

an > 0

a(n+5) = (-1)⁵ × 5^(n+5) < 0

a(n+10) = (-1)¹⁰ × 5^(n+10) > 0

a(n+15) = (-1)¹⁵ × 5^(n+15) < 0

Since a^n is positive, n is even

Odd powers of -1 are negative

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