MYTUTOR SUBJECT ANSWERS

174 views

Solve the following simultaneous equation: 3x+2y=20 and x+4y=20

In this example, we want to find values for both x and y which are our unknowns. 

So we start by rearranging x to be on its own but still in terms of y. We then can plot it into the next equation. 

Hence we get the following equations:

.  x=20-4y (See, 4y has been taken over to the other side and hence the sign changes)

.  3x+2y=20

Then we substitute this new value of x in the other equation:

3(20-4y)+2y=20

60-12y+2y=20 (we have multiplied out the 3 and its bracket to simplify)

-10y=20-60 (make sure you change the sign when taking the 60 across!)

-10y=-40

-y=-4 (here we divided 40 by 10)

y=4 (the minus signs cancel each other out)

Now that you've found y we must plot it back into the original equation to find x:

x+4y=20

x+4(4)=20

x+16=20

x=20-16

x=4

Therefore, x=4 and y=4.

Phillipa S. 13 Plus  Maths tutor

4 months ago

Answered by Phillipa, a 13 Plus Maths tutor with MyTutor


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

116 SUBJECT SPECIALISTS

£20 /hr

Irfan S.

Degree: Computer Science (Bachelors) - Manchester University

Subjects offered: Maths

Maths

“I am a computer science student at the University of Manchester. Teaching has always been a hidden passion of mine and unlike most I actually enjoyed my time in high school.  The sessions will be completely tailored to the you where I...”

£18 /hr

Dharani Y.

Degree: Medicine (Bachelors) - Kings, London University

Subjects offered: Maths, Science+ 4 more

Maths
Science
Chemistry
Biology
-Personal Statements-
-Medical School Preparation-

“A little bit about me: Hi, I’m Dharani! I am a medical student at King’s College London. I have some experience in mentoring as I used to help younger students on a one-to-one basis at school during classes. The idea of being able to ...”

MyTutor guarantee

£18 /hr

Olivia K.

Degree: Philosophy, Politics and Economics (Bachelors) - Oxford, Magdalen College University

Subjects offered: Maths, Politics+ 3 more

Maths
Politics
Philosophy and Ethics
.TSA. Oxford.
-Oxbridge Preparation-

“About Me: I am a second year student at Oxford studying Philosophy, Politics and Economics. I have a real passion for Politics, specialising in American studies and British government in the last 100 years but I also come from a very ...”

MyTutor guarantee

About the author

£18 /hr

Phillipa S.

Degree: Engineering (Masters) - Exeter University

Subjects offered: Maths

Maths

“About me: Hello guys! I'm Phillipa and am currently in my second year at Exeter University doing Civil and Environmental Engineering. So maths maths maths. Super keen on tutoring, I worked with kids aged 13 and 15 with their homewo...”

MyTutor guarantee

You may also like...

Other 13 Plus Maths questions

How do you simplify numbers with powers?

Factorise the following a) 8x + 6y b) 7xy + 3xzy c)5xyz - 20x^2y^2z

Solve the equation 3x + 11 = 56

What is the median, upper quartile and lower quatile. How do we find them?

View 13 Plus 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