Answer:
12.8 seconds
Step-by-step explanation:
Create a proportion where x is the number of seconds for 80 feet
= 
Cross multiply and solve for x
25x = 320
x = 12.8
So, the answer is 12.8 seconds
Answer:
Step-by-step explanation:
Show that if 3x – 7 = 5, then x = 4.
Here, our given statement is 3x – 7 = 5, and we're asked to prove x = 4.
x=4
Statements Reasons
1. 3x – 7 = 5 Given
2. 3x – 7 + 7 = 5 + 7 Addition of 7 to equation (1)
3. 3x + 0 = 5 + 7 Substitution of –7 + 7 = 0 into (2)
4. 3x = 5 + 7 Substitution of 3x + 0 = 3x into (3)
5. 3x = 12 Substitution of 5 + 7 = 12 into (4)
6. 3x⁄3 = 12⁄3 Dividing equation (5) by 3
7. x = 12⁄3 Substitution of 3x⁄3 = x into (6)
8. x = 4 Substitution of 12⁄3 = 4 into (7)
Is there such a thing as being too descriptive? Yep, and that was it, since over half the proof was devoted to telling the reader how to do arithmetic. We'll typically take numerical computation for granted, and write proofs like this:
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.
Answer:
uh okay I'm just stumbling upon questions like this
Answer:
(-5, 6) is not a solution.
Step-by-step explanation:
6=2(-5)+4
6=-10+4
-10+4=-6, not 6.
