PLEASE HELP VERY LAST QUESTION
1 answer:
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The correct answer is C) t₁ = 375, 
.
From the general form,
, we must work backward to find t₁.
The general form is derived from the explicit form, which is
. We can see that r = 5; 5 has the exponent, so that is what is multiplied by every time. This gives us
Using the products of exponents, we can "split up" the exponent:
We know that 5⁻¹ = 1/5, so this gives us
Comparing this to our general form, we see that
Multiplying by 5 on both sides, we get that
t₁ = 75*5 = 375
The recursive formula for a geometric sequence is given by
, while we must state what t₁ is; this gives us
From the general form,
The general form is derived from the explicit form, which is
Using the products of exponents, we can "split up" the exponent:
We know that 5⁻¹ = 1/5, so this gives us
Comparing this to our general form, we see that
Multiplying by 5 on both sides, we get that
t₁ = 75*5 = 375
The recursive formula for a geometric sequence is given by
Let's assume that Kirby walks with a speed
for a time
, and that he runs with a speed
for a time
.
The total time available for Kirby to catch the train is:
and this must be equal to the sum of the two times t1 and t2:
The distance Kirby should cover is
and this should be equal to the sum of the distances covered by walking and by running:
So we have a system of 2 equations:
If we solve the system, we find:
So, Kirby needs to run at least for 8 minutes in order to catch the train.
for a time
for a time
The total time available for Kirby to catch the train is:
and this must be equal to the sum of the two times t1 and t2:
The distance Kirby should cover is
and this should be equal to the sum of the distances covered by walking and by running:
So we have a system of 2 equations:
If we solve the system, we find:
So, Kirby needs to run at least for 8 minutes in order to catch the train.