4 cm 5 cm
6 cm
6 cm
Which is the surface area of the pyramid
A. 48 cm
B. 51 cm2
C. 60 cm?
O D. 84 cm
O E 96 cm

hello from mrbilldoesmath!

answer:

a(n) - a(n-1) -3

discussion:

this ones a bit interesting. given a(n) = 5 - 3n consider this:

a(n-1) = 5 - 3(n-1)

          = (5 - 3n) + 3             => but a(n) = 5 - 3n, the first term

          = a(n)   + 3                 => subtract 3 from both sides

a(n-1) -3 = a(n)  

or

a(n) - a(n-1) -3

you,

mrb

right

step-by-step explanation: