Evaluate the expression when c=9 and d=7.
4c-d

29

Step-by-step explanation:

plug in c=9 and d=7 to the equation.

it'll look like this

4(9) - 7

4 x 9 is 36

36 - 7 = 29

Final answer = 29

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