1) Solve for t:
30(0.85^t)=60
2) Solve for t:
7^t=8^t+1
Thank you in advance!
30(0.85^t)=60
2) Solve for t:
7^t=8^t+1
Thank you in advance!
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First, it's easier to deal with separate questions in separate posts, but I'll deal with these:
1) Divide both sides by 30 to get
(0.85^t) = 2
Take log of both sides
log (0.85^t) = log 2
Use properties of logs
t log (0.85) = log 2
and divide
t = (log 2)/(log 0.85)
2) I have to assume you mean 7^t = 8^(t+1),
since their is no solution to 7^t = (8^t) + 1
Take log of both sides
log (7^t) = log (8^(t+1))
Use properties of logs
t log 7 = (t+1) log 8
Distribute
t log 7 = t log 8 + log 8
t log 7 - t log 8 = log 8
t (log 7 - log 8) = log 8
t = (log 8)/(log 7 - log 8)
3) Use properties of logs to rewrite left side of equation
log (4t^2) = 2
Exponentiate both sides to the power of 10
10^(log(4t^2)) = 10^2
Simplify
4t^2 = 100
t^2 = 25
t = 5
1) Divide both sides by 30 to get
(0.85^t) = 2
Take log of both sides
log (0.85^t) = log 2
Use properties of logs
t log (0.85) = log 2
and divide
t = (log 2)/(log 0.85)
2) I have to assume you mean 7^t = 8^(t+1),
since their is no solution to 7^t = (8^t) + 1
Take log of both sides
log (7^t) = log (8^(t+1))
Use properties of logs
t log 7 = (t+1) log 8
Distribute
t log 7 = t log 8 + log 8
t log 7 - t log 8 = log 8
t (log 7 - log 8) = log 8
t = (log 8)/(log 7 - log 8)
3) Use properties of logs to rewrite left side of equation
log (4t^2) = 2
Exponentiate both sides to the power of 10
10^(log(4t^2)) = 10^2
Simplify
4t^2 = 100
t^2 = 25
t = 5
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1.
30(0.85^t)=60 given
0.85^t = 2 divide both sides of "=" by 30
ln(0.85^t) = ln(2) take logs of both sides of "="
t·ln(0.85) = ln(2) ln(aⁿ) = nln(a)
t = ln(2)/ln(0.85) simplify
t ≈ -4.26502428 According to google
2.
7^t=8^t + 1 given
3.
2log(t)+log(4)=2 given
log(4t²) = log(100) assuming base 10 (logs)
4t² = 100
t² = 25
t = 5
The library I am at is closing, so, I didn't get to #2. I hope what I have helps. I'd like to know how to figure #2; e-mail me if you want. Good luck!
30(0.85^t)=60 given
0.85^t = 2 divide both sides of "=" by 30
ln(0.85^t) = ln(2) take logs of both sides of "="
t·ln(0.85) = ln(2) ln(aⁿ) = nln(a)
t = ln(2)/ln(0.85) simplify
t ≈ -4.26502428 According to google
2.
7^t=8^t + 1 given
3.
2log(t)+log(4)=2 given
log(4t²) = log(100) assuming base 10 (logs)
4t² = 100
t² = 25
t = 5
The library I am at is closing, so, I didn't get to #2. I hope what I have helps. I'd like to know how to figure #2; e-mail me if you want. Good luck!
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1. 30(0.85)^t = 60
take ln both sides
ln[30(0.85)^t] = ln60
ln30+t*ln(0.85) = ln(30*2) = ln30+ln2
t*ln(0.85) = ln2
t = ln2/ln(0.85)
t = -4.265(approx)
2. 7^t = 8^t+1
'+1' is the disturbing element!
Wait!
take ln both sides
ln[30(0.85)^t] = ln60
ln30+t*ln(0.85) = ln(30*2) = ln30+ln2
t*ln(0.85) = ln2
t = ln2/ln(0.85)
t = -4.265(approx)
2. 7^t = 8^t+1
'+1' is the disturbing element!
Wait!
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Tell your teacher you slept through the lecture on the quadracti equation.
Those problems are very easy for anyone who was awake in class.
Those problems are very easy for anyone who was awake in class.
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I think u have to apply the distributive property.