MYTUTOR SUBJECT ANSWERS

358 views

How do i solve simultaneous equations?

simulatneous equations are solved by eliminating one of the unknowns such as x or y. there are a number of ways to do this such as substitution or subtraction/addition. For this example we will use subtraction addition as i always found that the easier method at GCSE since it often avoids fractions.

e.g. 2y=3x+12 and 3y=5x+14

we need to choose one of the two unknowns to eliminate and then find their lowest common denominator. I will choose x, where the LCD is 15 (3*5=15). now we multiply the entire equation through in order that the number in front of x (called the coefficient) is 15. in the first equation, we multiply through by 5.

(2*5)y=(3*5)x+(12*5)

10y=15x+60

in the second equation we multiply through by 3 like before

(3*3)y=(5*3)x+(14*3)

9y=15x+42

now both the coefficients of x are 15 so we can subtract one equation from the other

(10-9)y=(15-15)x+(60-42)

y=0x+18

y=18

we now have the y value, since x is now zero. to find the x value all we need to do is go back to one of the first equations and put the value y=18 into the equation to resolve for x.

(2*18)=3x+12

36-12=3x

24=3x

x=8

and thats everything. By making sure we can subtract one equation from another to eliminate one of the unkowns we can subsequently obtain both values. in this case, y=18 and x=8 

Matthew K. GCSE Maths tutor, GCSE Physics tutor

1 year ago

Answered by Matthew, a GCSE Maths tutor with MyTutor

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

325 SUBJECT SPECIALISTS

£22 /hr

Ben C.

Degree: Mathematics (Bachelors) - Warwick University

Subjects offered: Maths, Spanish+ 2 more

Maths
Spanish
Biology
.STEP.

“Hi I'm Ben, I'm a maths undergraduate at Warwick University with some previous tutoring experience.”

£18 /hr

Jonathan T.

Degree: Biological Sciences (with placement) (Bachelors) - Durham University

Subjects offered: Maths, Chemistry+ 1 more

Maths
Chemistry
Biology

“About me:I am a Biology student studying at Durham University but currently working in Cambridge on my year in Industry. I love all things Science and have a huge passion for sharing my knowledge in the field and developing others ...”

£18 /hr

James K.

Degree: Law with Accounting and Finance (Bachelors) - Liverpool University

Subjects offered: Maths, Law+ 1 more

Maths
Law
Business Studies

“About Me: I am currently studying Law with Accounting and Finance (LLB Hons) at the University of Liverpool. I have always had a real passion and love for Maths, Economics, Business and reccently discovered Law and hope that my tutori...”

MyTutor guarantee

About the author

£22 /hr

Matthew K.

Degree: General Engineering (Masters) - Warwick University

Subjects offered: Maths, Physics

Maths
Physics

“About MeI am a student studying a general engineering masters degree at Warwick University. I amfun and friendly and have a passion for maths and physics with a little bit of rugby on the side.I helped my brother whilst he was ...”

You may also like...

Posts by Matthew

How do I find the coordinates of maximum and minimum turning points of a cubic equation?

How do i solve simultaneous equations?

How to i calculate total resistance in a circuit?

Other GCSE Maths questions

How to add fractions

What is 'cotx'?

Work out the points of intersection of the graphs of y= (x+2)(x-4) and y=3x+6.

GCSE Maths - Solve the equation (2x+3)/(x-4) - (2x-8)/(2x+1) = 1 Give your answer to 2 decimal places.

View GCSE Maths tutors

Cookies:

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

mtw:mercury1:status:ok