23 . C
The best way to go about this one is to check out each answer choice, trying to think of a
case where that choice is not true. The correct answer is the one that has no
counterexample. That a + b > 0 and c + d > 0 would imply, for example, that the total sum a +
b + c + d would also be positive, but that’s not the same as saying (A), a + b + c > 0. If a = 3, b =
−2, c = −4, and d = 5, then (A) is not true. Nor is (B). (C) is true for this set of numbers and for
any possible set of numbers because a^2 + b^2 will be greater than zero as long as a and b are
not both zero.24 . B
It’s given that x > 0, so |x| = x.25 . C
What you have here is a quadratic equation in which the unknown is sin x. To make things
simpler, replace sin x with y and solve for y:
It’s given that x is a positive acute angle, so 0 < sin x < 1, and only 0.40 fits.26 . B
If the solutions to ax^2 + bx + c = 0 are 3 ± 2i, then