SG #1 Algebra Chapter 7 Medium Questions #6

[johnhurford]

I approached this problem as follows

(p/q)^2=4

Rewriting the exponent
p^2/q^2 = 4

Multipying both sides by q^2
p^2=4*q^2

Square rooting both sides
p = 2q

which I know is a answer, so I marked C (which is wrong). Given my approach how would I determine that D is the answer? Maybe i need to brush up on my roots?I I'm thinking my approach is not good and that I should just plug numbers for problems like these.

[tommywallach]

Hey John,

Really the only issue is that when you're square rooting an expression with a variable, you have to be ready for two solutions. That's the danger here. If you plug numbers, you can see the issue. Try 2/1 and -2/-1.

-t