If g(x) is the inverse of f(x), what is the value of f(g(2))?
2 answers:
Answer:
2
Step-by-step explanation:
So to figure this out we just need to flip the values of x and y in the table and then redefine that as the function g(x), because an inverse is essentially the reverse!
So if we flipped x and y's for f(x). We would see that our output or y of g(x) is -3 when x = 2, or in other words g(2) = -3. This means that we are now going to solve for when f(-3). So now lets look at the table and find the value at x = -3 for f(x). This value is 2, so the value of f(g(2)) = 2.
*In the future*
When you have a composite function of two inverses they essentially cancel out and would leave whatever the value of x is. So if we know f(x) and g(x) were inverses the value of f(g(2)) would just be 2.
For example:
ln(x) and e^x are inverses so if I had a composition like this:
The answer to this would be 2 because these inverse functions "'cancel" out
So
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Given Information:
Area of rectangle = 16 square feet
Required Information:
Least amount of material = ?
Answer:
x = 4 ft and y = 4 ft
Step-by-step explanation:
We know that a rectangle has area = xy and perimeter = 2x + 2y
We want to use least amount of material to design the sandbox which means we want to minimize the perimeter which can be done by taking the derivative of perimeter and then setting it equal to 0.
So we have
xy = 16
y = 16/x
p = 2x + 2y
put the value of y into the equation of perimeter
p = 2x + 2(16/x)
p = 2x + 32/x
Take derivative with respect to x
d/dt (2x + 32/x)
2 - 32/x²
set the derivative equal to zero to minimize the perimeter
2 - 32/x² = 0
32/x² = 2
x² = 32/2
x² = 16
x = ft
put the value of x into equation xy = 16
(4)y = 16
y = 16/4
y = 4 ft
So the dimensions are x = 4 ft and y = 4 ft in order to use least amount of material.
Verification:
xy = 16
4*4 = 16
16 = 16 (satisfied)