Which of the following expressions is a fourth root of unity?

Step-by-step explanation:

If in doubt, multiply them out.

  (-i)^4 = i^4 = 1 . . . . . results for ±i

  (-1)^4 = 1^4 = 1 . . . . . results for ±1

An even power of a negative number is equivalent to the same power of the opposite (positive) number. The even number of minus signs cancel in the final product.

In trig form, unity is 1∠(n·360°) . . . . . for n = any integer

Then the 4th root is ...

  1^(1/4) ∠(n·360°/4) = 1 ∠(n·90°) . . . . for n = 0...3 (angles repeat after that)

That is, the roots are ...

Of these, all but the first are listed among your answer choices. The appropriate selection is all of the above. (recognizing that not all of the appropriate choices are "above" that answer selection).

the answer is (2x+8)²= 16

let x be the money she spent so that she can earn the free t-shirt.

since, she already spent $112.49

⇒

also, as per the statement: jennifer must spend $250 or more in order to qualify for a free t-shirt at the store.

then,

we have an inequality i.,e

subtract 112.49 from both sides we get;

therefore, $137. 51 more money does jennifer need to spend so that she can earn the free t-shirt