Question

If s(x) = 2 – x2 and t(x) = 3x, which value is equivalent to (s circle t) (negative 7)?
a)–439
b)–141
c)153
d)443

Answer 1

What you have described here is a composite function. Here's a rundown of how composite functions work. Your question asks for this:
\[s∘t\]
Which is equivalent to
\[s(t(x))\]
Recall that f(x) simply means that it takes in an input of x as a function of f. This is the same scenario here. s(t(x)) simply takes in the input of t(x) to get an output of s(t(x)). Since we start off with our value of -7, we can plug that into our input value x to find t(x). The output of t(x) becomes the input of s(t(x)). Solving t(x) yields -21. Now plug in -21 to s(t) to find s(t(x)) at x = -21.