The nth term of a sequence is 2n-1.
the nth term of a difference sequence is 3n+1.
work out the three numbers in both the sequences between 20-40

25,31,37

Step-by-step explanation:

n should be positive integer number. The three numbers in both sequences have different term number n but same value. We can equalize each nth term in the question to "a" which represents one of the three numbers.

a=2n-1, then n=(a+1)/2

a=3n+1, then n=(a-1)/3

remember the two n above are different but both should be positive integer. That means, we have to find the "a" number that gives me an integer n for the first equation. The possible numbers between 20 to 40 are 22,25,28,31,34,37,40.

The possible numbers for the second equation are 21,23,25,27,29,31,33,35,37,39.

Now find the common numbers between the two sets above. They are 25,31,37

a.   since the profit made in 2012 is equal to the profit made in 2014, the profit is symmetric about the line y = 120,000.

step-by-step explanation:

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