Question

MULTIPLE CHOICE, PLEASE ANSWER
What are the values of the variable in 37 = 30 − x2?




A.−+i




B.−+3i2√




C.−+2i3√




D.−+i7√

Answer 1

@mathmale

Answer 2

@superdavesuper

Answer 3

Note that \(\large 37=30-x^2 \implies x^2=-7\). What do you get when you square root both sides? :-)

Answer 4

i dont know

Answer 5

A?

Answer 6

It's not A. Let's think about a slightly different problem. Suppose you want to find the solution to \(\large x^2=5\). If you take square roots of both sides, we get \(\large x=\pm\sqrt{5}\), which can't be simplified any further. Now, going back to your equation \(\large x^2=-7\), what do you get when you square root both sides? Also keep in mind that since you'll be taking a square root of a negative number, there will be an \(\large i\) term in your answer.

Does this clarify things? :-)

Answer 7

Hmmm... D? :)

Answer 8

Yes, D (\(\large x=\pm\sqrt{7}i\)) is the correct choice. Does that make a little more sense now? :-)