MYTUTOR SUBJECT ANSWERS

548 views

What is solution by substitution?

Simultaneous equations - Solution by substitution

As the variables (x & y) are the same in both equations, we can substitute from one equation into the other. This will give an equation with just one variable, which can easily be solved.

Example:

Equation 1   3y = 6x - 3

Equation 2   4y = 5x + 2

Make y the subject of equation 1, then substitute into equation 2:

·         Equation 1, divide both sides by 3 gives    y = 2x – 1

·         Equation 2, substitute for y from above gives  4(2x – 1) = 5x + 2

·         Multiply out brackets         8x – 4 = 5x + 2

·         Simplify and solve             3x = 6  therefore   x = 2

Substitute this value back into either of the original equations to solve for y:

Equation 1    3y = 6 (2) -3  therefore y = 3.

Key tip: Instead you could have made x the subject of an equation, and it can be either equation. Before you begin, think carefully about which variable will be easiest to make the subject of which equation.

 

Antonia M. A Level Chemistry tutor, A Level Maths tutor, GCSE Chemist...

2 years ago

Answered by Antonia, who tutored GCSE Maths with MyTutor


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

511 SUBJECT SPECIALISTS

£18 /hr

Evelin H.

Degree: Economics (Bachelors) - Durham University

Subjects offered:Maths, Economics+ 1 more

Maths
Economics
-Personal Statements-

“Hi! I’m Evelin, an undergraduate at Durham University. Having been a tutor before, I know how hard it can be to keep up with all the work. So why do it alone?”

£18 /hr

Charlotte S.

Degree: Modern Languages with a Year Abroad (French and Italian) (Bachelors) - Durham University

Subjects offered:Maths, French+ 4 more

Maths
French
Extended Project Qualification
Biology
.MLAT (Modern Languages)
-Personal Statements-

“I'm a modern languages student studying French and Italian at Durham University . I have ahuge passion for languages and absolutely love anything French or Italian related- from road signs to medieval French literature; I am mesmerised ...”

£18 /hr

Gabriella O.

Degree: Law (Bachelors) - Durham University

Subjects offered:Maths, Chemistry+ 3 more

Maths
Chemistry
Biology
.LNAT.
-Personal Statements-

“I am Gabriella and I am a 3rd year law student at Durham University. I love learning and would like to share this passion with you. I believe it important for everyone to achieve their best. Although I am studying law I took maths and ...”

About the author

PremiumAntonia M. A Level Chemistry tutor, A Level Maths tutor, GCSE Chemist...

Antonia M.

Currently unavailable: for new students

Degree: Chemistry (physical natural sciences) (Masters) - Cambridge alumni University

Subjects offered:Maths, Science+ 1 more

Maths
Science
Chemistry

“Science and Maths tutor from the University of Cambridge, keen to support you in getting top grades.”

You may also like...

Posts by Antonia

How do you calculate work done?

What is Le Chatelier's Principle?

What is solution by substitution?

Other GCSE Maths questions

I am getting stuck on how to solve Simultaneous Equations, can you explain how to do this?

How do i solve the quadratic x^2 + 5x + 6 = 0 ?

Surd Calculations?

How do I do the dot product with vectors?

View GCSE 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