21x + 28. just distribute the 7.
Hi there!
![\large\boxed{f^{-1}(x) = \sqrt[3]{\frac{x+4}{9} } }](https://tex.z-dn.net/?f=%5Clarge%5Cboxed%7Bf%5E%7B-1%7D%28x%29%20%3D%20%20%5Csqrt%5B3%5D%7B%5Cfrac%7Bx%2B4%7D%7B9%7D%20%7D%20%7D)

Find the inverse by replacing f(x) with y and swapping the x and y variables:

Isolate y by adding 4 to both sides:

Divide both sides by 9:

Take the cube root of both sides:
![y = \sqrt[3]{\frac{x+4}{9} }\\\\f^{-1}(x) = \sqrt[3]{\frac{x+4}{9} }](https://tex.z-dn.net/?f=y%20%3D%20%5Csqrt%5B3%5D%7B%5Cfrac%7Bx%2B4%7D%7B9%7D%20%7D%5C%5C%5C%5Cf%5E%7B-1%7D%28x%29%20%3D%20%5Csqrt%5B3%5D%7B%5Cfrac%7Bx%2B4%7D%7B9%7D%20%7D)
A picture can help.
The median to the long side divides the isosceles triangle into two right triangles with hypotenuse 10 and short leg 6. Thus the long leg (median of interest) is found by the Pythagorean theorem to be
... √(10² -6²) = √64 = 8
Then the midpoint of the short side is found to be 6 + (6/2) = 9 units to the side and 8/2 = 4 units above the opposite vertex. Hence the square of the length of that median is 9² + 4² = 97.
The sum of squares of interest is
... 8² + 2×97 = 258
B would be the answer. hope it helps !
The approximate length of rail that needs to be replaced is 7.1 ft
<h3>Length of arc</h3>
Since the pool is circular, the approximate length that needs to be replaced is an arc of length, L = Ф/360° × πD where
- Ф = central angle of rail section = 27° and
- D = diameter of circular pool = 30 ft
<h3>Approximate length of rail</h3>
So, substituting the values of the variables into the equation, we have
L = Ф/360° × πD
L = 27°/360° × π × 30 ft
L = 3/40 × π × 30 ft
L = 3/4 × π × 3 ft
L = 9/4 × π ft
L = 2.25 × π ft
L = 7.07 ft
L ≅ 7.1 ft
So, the approximate length of rail that needs to be replaced is 7.1 ft
Learn more about length of an arc here:
brainly.com/question/8402454