Answer:
Here we have that f(x) = 5x^2 - 100 and we want to find x, this would mean, isolate the value of x.
First, we add 100 in both sides of the equation to remove the leftmost therm:
f(x) + 100 = 5x^2 - 100 + 100 = 5x^2
Now, we divide by 5 in both sides.
(f(x) + 100)/5 = (5x^2)/5 = x^2
Now, we apply the square root in both sides:
(+/-)√((f(x) + 100)/5) = √x^2 = x
Now you have the value of x, when someone gives you the value of f(x), you can find the two values of x asociated with it (there are two values of x asociated because f(x) is a quadratic function
