For a function to be continuous at an x-value, say -17, you need to make sure two things line up:
The limit from the left equals the limit from the right.

This limit equals the functions value.

The left hand limit involves the first piece, f(x) = 20x + 1:
![\begin{aligned} \lim_{x \to -17^{-}} f(x) &= \lim_{x \to -17^{-}} (20x+1)\\[0.5em]&= 20(-17)+1\\[0.5em]&= -339\endaligned}](https://tex.z-dn.net/?f=%5Cbegin%7Baligned%7D%20%5Clim_%7Bx%20%5Cto%20-17%5E%7B-%7D%7D%20f%28x%29%20%26%3D%20%20%5Clim_%7Bx%20%5Cto%20-17%5E%7B-%7D%7D%20%2820x%2B1%29%5C%5C%5B0.5em%5D%26%3D%20%20%2020%28-17%29%2B1%5C%5C%5B0.5em%5D%26%3D%20%20%20-339%5Cendaligned%7D)
The right hand limit invovles the second piece, f(x) = -10x^2:
![\begin{aligned} \lim_{x \to -17^{+}} f(x) &= \lim_{x \to -17^{+}} (-10x^2)\\[0.5em]&= -10\cdot (-17)^2\\[0.5em]&= -2890\endaligned}](https://tex.z-dn.net/?f=%5Cbegin%7Baligned%7D%20%5Clim_%7Bx%20%5Cto%20-17%5E%7B%2B%7D%7D%20f%28x%29%20%26%3D%20%20%5Clim_%7Bx%20%5Cto%20-17%5E%7B%2B%7D%7D%20%28-10x%5E2%29%5C%5C%5B0.5em%5D%26%3D%20%20%20-10%5Ccdot%20%28-17%29%5E2%5C%5C%5B0.5em%5D%26%3D%20%20%20-2890%5Cendaligned%7D)
Since the two one-sided limits don't match, the function is not continuous at x=-17.
The solution would be like
this for this specific problem:
sin 54 degrees = Height/718.0624
Height = (sin 54 degrees)(718.0624) = 580.9 ft
So the height of the balloon is 580.9 ft. I am hoping that this
answer has satisfied your query and it will be able to help you in your
endeavor, and if you would like, feel free to ask another question.
1. Add -4.5 to 18.5
2. Divide 23 by 7
3. Then subtract 6 from -2.7