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Question:
Approximate log base b of x, log_b(x).
Of course x can't be negative, and b > 1.
Answer:
f(x) = (-1/x + 1) / (-1/b + 1)
Step-by-step explanation:
log(1) is zero for any base.
log is strictly increasing.
log_b(b) = 1
As x descends to zero, log(x) diverges to -infinity
Graph of f(x) = (-1/x + 1)/a is reminiscent of log(x), with f(1) = 0.
Find a such that f(b) = 1
1 = f(b) = (-1/b + 1)/a
a = (-1/b + 1)
Substitute for a:
f(x) = (-1/x + 1) / (-1/b + 1)
f(1) = 0
f(b) = (-1/b + 1) / (-1/b + 1) = 1
Answer:
2.0833
Step-by-step explanation:
2 3/4 + 3 1/2 =6.25
6.25(1/3)=2.0833
The inverse of this function is f(x) = 2x - 12.
You can find the inverse of any function by switching the f(x) and x values in the equation. Then you can solve for the new f(x) value. The result is your inverse function. The work for this one is below.
f(x) = 1/2x + 6 ----> switch f(x) and x
x = 1/2f(x) + 6 ----> subtract 6
x - 6 = 1/2f(x) ----> multiply by 2
2x - 12 = f(x) ----> change the order for consistency.
f(x) = 2x - 12
Example 2. Simple interest on $5000 over 4 years is $1800, what is the interest rate? Example 3. If you borrow $1200 at a 5% annual interest rate, how long will it take for the total amount owed to reach $1300? Example 4. Find the principal if the simple interest in 14 days at 25% per annum is 100.
