soumya1989 wrote:
If \(x^4 = 29x^2 - 100\), then which of the following is NOT a product of three possible values of x?
I. -50
II. 25
III.50
A. I only
B. II only
C. III only
D. I & II only
E. I & III only
Given: x⁴ = 29x² - 100
Rewrite as: x⁴ - 29x² + 100 = 0
Factor to get: (x² - 25)(x² - 4) = 0
Factor more to get: (x + 5)(x - 5)(x + 2)(x - 2) = 0
So, x = -5, 5, -2 or 2
(-5)(5)(2) = -50, so statement I is possible - ELIMINATE A, D, E
(-5)(5)(-2) = 50, so statement III is possible - ELIMINATE C
Answer: B
In other words, it is NOT possible to get a product of 25 using 3 of the possible x-values, the correct answer is B
Cheers,
Brent