So... hmmm if you check the first picture below, for 2)
we could use the proportions of those small, medium and large similar triangles like
now.. for 3) will be the second picture below
Answer:
C
Step-by-step explanation:
In general for arithmetic sequences, recursive formulas are of the form
aₙ = aₙ₋₁ + d,
and the explicit formula (like tₙ in your problem), are of the form
aₙ = a₁ + (n - 1)d,
where d is the common difference. So converting between the two of these isn't so bad. In this case, your problem wants you to have an idea of what t₁ is (well, every answer says it's -5, so there you are) and what tₙ₊₁ is. Using the formulas above and your given tₙ = -5 + (n - 1)78, we can see that the common difference is 78, so no matter what we get ourselves into, the constant being added on at the end should be 78. That automatically throws out answer choice D.
But to narrow it down between the rest of them, you want to use the general form for the recursive formula and substitute (n + 1) for every instance of n. This will let you find tₙ₊₁ to match the requirements of your answer choices. So
tₙ₊₁ = t₍ₙ₊₁₎₋₁ + d ... Simplify the subscript
tₙ₊₁ = tₙ + d
Therefore, your formula for tₙ₊₁ = tₙ + 78, which is answer choice C.
If 5 consecutive integers is 205,
then a + b + c + d + e = 205
but also, each integer is separated by a difference of 1
⇒ a + (a + 1) + (a + 2) + (a + 3) + (a + 4) = 205
⇒ 5a + 10 = 205
⇒ 5a = 195
⇒ a = 39
∴ third term = 39 + 2
= 41
If you multiply them all you get 3.0519273e+15 as your answer.
Answer:
19 is a prime number, thus making the only factors 1, 2, 19. (Not necessary to include 1)
Step-by-step explanation:
