Whenever the exponent is a multiple of 4, i n and (–i)n are both equal to 1.
(B) is the only multiple of 4 among the choices. When n = 24 , in + (–i)n = 1 +
1 = 2, which is a positive integer.39 . D
Between 0 and 2π, cos x ranges from –1 to 1. The maximum value of f(x) =
1 − cos x will be when cos x is at its least; that is, when cos x = –1:
40 . E
The triangle is isosceles; since AB = BC, x = z. Since y > 60, that leaves less
than 120 degrees to split between x and z, so x and z are both less than- Angle a is an exterior angle, so it’s equal to the sum of the remote
interior angles:
a = x + yNow you can see that II is true, because y > 60 and z < 60, and you can see
that III is true, because a = x + y and x = z. I is not true: y is greater than z
and a + z = 180, so a + y is greater than 180.41 . D
Imagine (or use your graphing calculator) the graph of
between 0 and 1. At x = 1, f(x) = 1. As x gets smaller, f(x) gets bigger: