What are the roots of 3x^2 + 13x + 4 ?

To find the roots, we solve the equation 3x2 + 13x + 4 = 0.

We could try factorising the equation, which gives us

(3x + 1)(x + 4) = 0

So the roots are x = -1/3 and x = -4.

Alternatively, we could use the quadratic formula;

x = (-b +/- sqrt( b2 - 4ac)) / 2a

[note that sqrt(x) is the square root of x]

So here;

x= (-13 +/- sqrt(132 - 434)) / 2*3

   = (-13 +/- sqrt(169 - 48)) / 6

   = (-13 +/- sqrt(121)) / 6

   = (-13 +/- 11) / 6

   = (-13 + 11) / 6     or     (-13 - 11) / 6

   = -2 / 6      or      -24 / 6

   = -1 / 3      or      -4

So again, the roots are x = -1 / 3 or x = -4.

NB
Answered by Nicholas B. Maths tutor

10277 Views

See similar Maths A Level tutors

Related Maths A Level answers

All answers ▸

A small stone is projected vertically upwards from a point O with a speed of 19.6m/s. Modelling the stone as a particle moving freely under gravity, find the length of time for which the stone is more than 14.7 m above O


When you integrate a function why do you add a constant?


How to do the chain rule.


A curve is defined by the parametric equations; x=(t-1)^3, y=3t-8/(t^2), t~=0. Find dy/dx in terms of t.


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:

© 2025 by IXL Learning