The quadratic equation 2x^2 + 8x + 1 = 0 has roots a and b. Write down the value of a + b, a*b and a^2 + b^2.

Using Vieta's formulas, which make the correspondence between the sums and products of the roots of a polynomial and its coefficients, we can deduce that a + b = (-8)/2 = -4, ab = 1/2 =0.5 and a^2 + b^2 = (a+b)^2 - 2ab = (-4)^2 - 2*0.5 = 16 - 1 = 15. 

AI
Answered by Andreea I. Maths tutor

6270 Views

See similar Maths A Level tutors

Related Maths A Level answers

All answers ▸

Derive the quadratic equation.


How to expand squared brackets?


How do I know which is the null hypothesis, and which is the alternative hypothesis?


Do the following vector equations intersect? l = (1 + μ)i + (2 - μ)j + (2μ - 5)k, and m = 2λi + 3j + (2 + λ)k.


We're here to help

contact us iconContact ustelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

MyTutor is part of the IXL family of brands:

© 2026 by IXL Learning