If a and b are the roots of the quadric polynomial 2x^2+6x+7 what are a+b and ab?

The phrase "a and b are roots of 2x^2+6x+7" is just a way of saying that x=a and x=b solve the equation 2x^2+6x+7=0. Check out that by diving by 2 on both sides of this equation we get that that x=a and x=b solve x^2+3x+3.5=0. So a and b are roots of the polynomial x^2+3x+3.5, which has leading coefficient 1. Therefore it can be written as x^2+3x+3.5=(x-a)(x-b)=x^2-(a+b)x+ab. Equating coefficients of same degree: a+b=-3 ab=3.5

Answered by Guillermo C. Maths tutor

2464 Views

See similar Maths GCSE tutors

Related Maths GCSE answers

All answers ▸

Use completing the square to find the minimum of y = x^2 - 4x + 8


What is "Standard Form"?


ABC is an acute-angled triangle. BA=7cm and BC=8cm. The area of triangle ABC is 18 cm^2 . Work out the size of angle BAC. Give your answer correct to 3 significant figures. You must show all your working.


What is the fraction of blue beads?


We're here to help

contact us iconContact usWhatsapp logoMessage us on Whatsapptelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

© MyTutorWeb Ltd 2013–2024

Terms & Conditions|Privacy Policy