What is the sum of the squares of the roots of x^2 + 2x - 8 = 0?
Answer and explanation
Correct answer: C. 20
- Step 1: By Vieta, the sum of the roots is -2 and their product is -8.
- Step 2: x1^2 + x2^2 = (x1 + x2)^2 - 2 x1 x2 = 4 - (-16) = 20.
Answer
20.
Why not the others: 4 is the square of the sum; -12 adds 2p instead of subtracting it.
Practise more Algebra and complex numbers.
Free questions with an explanation for every one, and full timed Bagrut (Secondary School Matriculation) mock tests.
More Algebra and complex numbers questions
- What is the modulus of the complex number z = 2 + 2i?
- What is the sum of the squares of the roots of x^2 - 3x - 4 = 0?
- Solve e^x = 3.
- What is the remainder when 2x^3 + 2x^2 + 5x + 2 is divided by (x - 2)?
- What is the sum of the roots of 3x^2 + 9x + 4 = 0?
- What is the sum of the squares of the roots of x^2 - 3x - 10 = 0?