## MYTUTOR SUBJECT ANSWERS

701 views

### Factorise and solve x^2 - 8x + 15 = 0

The question gives you a hint on how to go about this question - Factorise!!

1) Factorise the left hand side. Find the two numbers which will add to give -8 and multiply to give 15. In this case, -3 and -5.

(x-3)(x-5)=0

2) Each set of brackets can equal 0. If a multiplication is equal to 0, then at least one term must be 0 itself.

x-3=0, x-5=0

3) Solve the equations.

x=3 or 5

4) CHECK!! Plug your values of x into the original equation to make sure you are right - an easy way to stop making silly mistakes!

When x=3, 32-(8x3)+15 = 9-24+15=0  (correct)

When x=5, 52-(8x5)+15 = 25-40+15=0 (correct)

1 year ago

Answered by Kieran, a GCSE Maths tutor with MyTutor

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

#### 808 SUBJECT SPECIALISTS

£20 /hr

Degree: Economics (Bachelors) - Cambridge University

Subjects offered:Maths, Economics+ 2 more

Maths
Economics
-Personal Statements-
-Oxbridge Preparation-

“Economics Graduate from Cambridge, wanting to share my passion for the discipline”

£24 /hr

Degree: Medical Sciences (Bachelors) - Exeter University

Subjects offered:Maths, Science+ 4 more

Maths
Science
Physics
Chemistry
Biology
-Personal Statements-

“Hi, I'm James, a Biology Masters graduate. I'm really passionate about science, and I hope i can share some of my interest with you!”

£24 /hr

Degree: PGCE Secondary Mathematics (Other) - Leeds University

Subjects offered:Maths, Further Mathematics

Maths
Further Mathematics

“I am currently completing 2 PGCEs in Leeds. I have always had a passion for maths and my objective is to help as many as possible reach their full potential.”

#### About the author

Currently unavailable: for regular students

Degree: Spanish and History (Bachelors) - Southampton University

Subjects offered:Maths, History

Maths
History

“About Me I am a first year student at the University of Southampton, studying Spanish and History. Although I eventually chose to follow humanities, I was always split as to what I prefered - at A Level I was so unsure I ended up taki...”

MyTutor guarantee

### You may also like...

#### Posts by Kieran

Factorise and solve x^2 - 8x + 15 = 0

How do I analyse a source?

What is the subjunctive and when should it be used?

#### Other GCSE Maths questions

Rationalise 1/(√7) ?

Solve the simultaneous equation: 2x + 3y = 6, 3x + 2y = 5.

Solve these equations simultaneously: (1) 5x - 10z = -45 and (2) 9x = -5z + 80

if x^2 + 9x + 20 = 0, what are the possible values of x?

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