Algebra Questions

Multiple choice
  1. $\dfrac{a^{2}-c^{2}}{4}$ and $\dfrac{a^{2}}{4}$
  2. $\dfrac{a^{2}+c^{2}}{4}$ and $\dfrac{a^{2}}{4}$
  3. $\dfrac{a^{2}-c^{2}}{2}$ and $\dfrac{a^{2}}{4}$
  4. $None\ of\ these$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Let roots be r1, r2. r1+r2 = a, r1*r2 = b. |r1-r2| < c => (r1-r2)^2 < c^2 => (r1+r2)^2 - 4r1r2 < c^2 => a^2 - 4b < c^2 => 4b > a^2 - c^2 => b > (a^2 - c^2)/4. Also, for real roots, D >= 0 => a^2 - 4b >= 0 => b <= a^2/4.

Multiple choice
  1. attest one root in [0, 1/2]

  2. attest one root in $\left[ -\dfrac { 1 }{ 2 } ,0 \right] $
  3. attest one root in [1, 2]

  4. None of these

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Interpreting the garbled condition as no two of a, b, and c being equal, the determinant condition reduces to 2a + b + c = 0. Substituting this relation into the quadratic shows that at least one root lies between 0 and 1/2.