Question

The function T(n) is defined below. Which of the following are equal to T(8)? Check all that apply.

Answer 1

You are told to choose the choices equal to T(8). T(8) means that you need to find the possible ways to write the y-value when n = 8, since 8 is being substituted in for "n."

1) First, plug in n = 8 into the equation you're given, T(n) = 4n - 5:
T(8) = 4(8) - 5
T(8) = 32 - 5
T(8) = 27

That is answer choice C, making choice C correct. You can eliminate choice B, since 27 ≠ 37.

2) Check answer choice A. Is T(5) + T(3) = 27? T(5) means you need to plug in 5 for n. T(3) means you need to plug in 3 for n.
T(5) + T(3)
=  [4(5) - 5] +  [4(3) - 5]
= [20-5] + [12-5]
= 15 + 7
= 22 

Since 22 ≠ 27, you can eliminate choice A.

3) Check answer choice D. Is T(7) + 4 = 27? T(7) means you need to plug in 7 for n.
T(7) + 4 
= [4(7) - 5] + 4 
= [28 - 5] + 4
= 23 + 4
= 27

Since 27 = 27, answer choice D is also correct!

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Answer: Choice C (27) and Choice D (T(7) + 4)