MYTUTOR SUBJECT ANSWERS

627 views

Solve x^2 + 8x +3 = 0 by completing the square.

Using the completing the square method:

1. Notice (x+4)2 = x2 + 8x +16 which differs from the question by a constant

2. So we can write: 

x2 + 8x + 3 = (x+4)2 - 13      (check this yourself if you don't see it immediately)

3. So from the question we get:

(x+4)-13 = 0

(x+4)= 13     (by adding 13)

x+4 = +-sqrt(13)    (square root remembering to include the +-)

x = -4 +-sqrt(13)      (subtracting 4)

So we have answers of:

x = - 4 + sqrt(13)

x = - 4 - sqrt(13)

which can both be checked by substitution into the original equation.

Lloyd S. GCSE Maths tutor, A Level Maths tutor, GCSE Physics tutor

1 year ago

Answered by Lloyd, an A Level Maths tutor with MyTutor


Still stuck? Get one-to-one help from a personally interviewed subject specialist

354 SUBJECT SPECIALISTS

£26 /hr

Daniel K.

Degree: Mathematical and Theoretical Physics (Masters) - Oxford, Merton College University

Subjects offered:Maths, Science+ 5 more

Maths
Science
Physics
Further Mathematics
Chemistry
.MAT.
-Personal Statements-

“Mathematics and Theoretical Physics, University of Oxford. I enjoy sharing my experience and enthusiasm in Maths with those who could do with some help”

PremiumGeorge B. GCSE Maths tutor, A Level Maths tutor, A Level Further Math...
£26 /hr

George B.

Degree: Mathematics (Masters) - Warwick University

Subjects offered:Maths, Further Mathematics + 1 more

Maths
Further Mathematics
.STEP.

“Premium tutor. First class graduate with teaching experience from a top Russell Group university. I deliver fun and relaxed lessons which achieve results!”

£22 /hr

Leon P.

Degree: Mathematics (Bachelors) - Imperial College London University

Subjects offered:Maths

Maths

“21 years old. 2 years experience teaching. BSc Mathematics Imperial College London. Studying MSc in Aerospace Dynamics (please ask for references).”

About the author

Lloyd S.

Currently unavailable: for regular students

Degree: Mathematics G100 (Bachelors) - Bristol University

Subjects offered:Maths, Further Mathematics

Maths
Further Mathematics

“About Me:I am 19 and from Devon, currently in my first year studying Maths at the University of Bristol. I have a real passion for Maths and I really hope I can help you to understand, and maybe even enjoy doing maths - I know not ev...”

You may also like...

Other A Level Maths questions

What's the deal with Integration by Parts?

Write tan(3x) in terms of tan(x). Hence show that the roots of t^3 - 3t^2 - 3t + 1 = 0 are tan(pi/12), tan(5pi/12) and tan(3pi/4)

Differentiate y=x^3*(x^2+1)

What is the factor theorem?

View A Level Maths tutors

We use cookies to improve your site experience. By continuing to use this website, we'll assume that you're OK with this. Dismiss

mtw:mercury1:status:ok