PSAT 8/9 Math Practice Test

Solving this kind of equation involves isolating the x^2 term and then taking the square root. Divide both sides by 3 to get x^2 = 9. The square root of 9 is 3, but x^2 = 9 means x can be either 3 or -3. Among the roots, the positive value is 3. The other options don’t satisfy the positive requirement: 9 and -9 would imply x^2 = 81, which makes 3x^2 equal to 243, not 27. Note that -3 is also a valid solution to the equation, just not the positive one requested.