2017 · Q17
If α and β are the roots of the equation x²+px+q=0, then what is α²+β² equal to ?
Elementary MathematicsAlgebra
- Ap²-2q
- Bq²-2p
- Cp²+2q
- Dq²-q
Explanation
α + β = −p and αβ = q. Then α² + β² = (α+β)² − 2αβ = p² − 2q: option A. Option C (p² + 2q) gets the sign of the 2αβ term wrong.