Begin to solve the equation 4.18x = 36.54 by taking the natural logarithm of both sides. Use
the calculator when it is time to find the approximate value of x.
42 . A
Before solving the question, be sure you understand the difference between the meanings of
f and f(x). The letter f can refer to a function. Other letters, like g, u, and t can also refer to
functions. Then f(x), which is read “f of x,” means the value of the function f at x.
The idea in the solution to this question is that the function of the inverse function of x is x. If
f−1 is the inverse function of the function f, then f(f−1(x)) = x. Here you are working with the
sine function and the inverse sine function. If you say that f(x) = sin x, then f−1(x) = arcsin x. So
sin (arcsin x) = x. If , then since sin (arcsin x) = x, ; (A) is correct.
Let’s briefly review the definition of the inverse sine function. The definition of the inverse
sine function, which is called arcsin x, is this. If −1 ≤ x ≤ 1, then arcsin x is that value y such
that and sin y = x. In order for g to be a function, to each x of the domain of g,
g must specify exactly one value. That is, for each specified x, g(x) is not ambiguous. Now
when x increases from to , sin x increases from −1 to 1, so the inverse sine function
arcsin x assigns exactly one value y such that to each x such that −1 ≤ x ≤ 1.
43 . C
In this question, you want the constant d, where if n is an integer and n ≥ 1, d = an + 1 − an.
In an arithmetic sequence, if a 1 is the first term and an is the nth term, then the sum Sn of the
first n terms can be found by using the formula . Using the formula with
a 25 = 104, S 25 = 1,400, and n = 25, you can find a 1 :
and a 1 = 8.