Solve the equation x^2 + 8x = -15

We first notice it's a quadratic equation in x so we want to make one side of the equation equal to 0.By adding 15 to both sides we get : x2 + 8x + 15 = 0We then look for two numbers which multiply to 15 and add to make 8 to help us factorise the LHS . The numbers are 3 and 5 so the equation becomes: (x+3)(x+5) = 0Therefore either x + 3 = 0 so x1 = -3or x + 5 = 0 so x2 = -5

Answered by Georgina L. Maths tutor

2547 Views

See similar Maths GCSE tutors

Related Maths GCSE answers

All answers ▸

A curve (a) has equation, y = x^2 + 3x + 1. A line (b) has equation, y = 2x + 3. Show that the line and the curve intersect at 2 distinct points and find the points of intersection. Do not use a graphical method.


Express the recurring decimal 0.2131313 as a fraction


The equation of the line L1 is y = 3x – 2 The equation of the line L2 is 3y – 9x + 5 = 0 Show that these two lines are parallel.


f(x) = 2x+3/x-4 Work out f ^–1 (x)


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
Cookie Preferences