Q. Logarithmic and exponential inversesFind the inverse of f(x)=bx and then prove that they are inverses.
Understand Inverse Function Concept: Understand the concept of an inverse function. An inverse function reverses the effect of the original function. If f(x)=y, then the inverse function f−1(y)=x. For the function f(x)=bx, we need to find a function that will give us the original x when we input y.
Express Function in Terms of y: Express the function in terms of y.Let's write the original function with y instead of f(x): y=bx.
Solve for x in Terms of y: Solve for x in terms of y.To find the inverse, we need to solve for x: x=logb(y). This means that the inverse function f−1(y) is the logarithm base b of y.
Write Inverse Function: Write the inverse function.The inverse function is f−1(y)=logb(y).
Prove Functions are Inverses: Prove that f and f−1 are inverses.To prove that two functions are inverses, we need to show that f(f−1(y))=y and f−1(f(x))=x.
Apply f to f−1: Apply f to f−1. Let's apply f to f−1(y): f(f−1(y))=f(logb(y))=blogb(y).
Simplify Expression: Simplify the expression.Using the property of logarithms that blogb(y)=y, we simplify the expression to get f(f−1(y))=y.
Apply f−1 to f: Apply f−1 to f. Now let's apply f−1 to f(x): f−1(f(x))=f−1(bx)=logb(bx).
Simplify Expression: Simplify the expression. Using the property of logarithms that logb(bx)=x, we simplify the expression to get f−1(f(x))=x.
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