Which one of the following is an arithmetic senquence?

A. .35, .5, .85, 1.1, 1.22, . . .

B. 5, 0, -1, -3, -7, . . .

C. 2, 3, 5, 7, 11, 13, 17, . . .

D. -2, 1, 4, 7, 10, . . .

  D.  -2, 1, 4, 7, 10

Step-by-step explanation:

An arithmetic sequence has a common difference between terms. We can see if the offered choices have that characteristic:

  A. .5 -.35 = .15; .85 -.5 = .35 ≠ .15 . . . . not an arithmetic sequence

  B. 0 -5 = -5; -1 -0 = -1 ≠ -5 . . . . not an arithmetic sequence

  C. 3 -2 = 1; 5 -3 = 2 ≠ 1 . . . . not an arithmetic sequence

  D. 1 -(-2) = 3; 4 -1 = 3; 7 -4 = 3; 10 -7 = 3 . . . . common difference of 3, an arithmetic sequence

The appropriate choice is ...

  D.  -2, 1, 4, 7, 10, ...

area of part 1:

a1=base*height/2=(8+2)*(8-2-2-1)/2=10*3/2=15 ft^2

area of part 2:

a2=length*width=(8+2)*1=10 ft2

area of part 3:

a3=length*width=8*2=16 ft2

total shaded area : a1+a2+a3=41 ft2

total area of the reactangle : a=16*8=128 ft2

total area of the nonshaded region : 128-41=87 ft2