MYTUTOR SUBJECT ANSWERS

160 views

Solve the simultaneous equations: 5x + 3y = 9 and 7x - 2y = 25.

To solve these similar equations, we must either first eliminate x or y. There are multiple ways of doing this, one being rearranging one of the equations so that it is either "x=.." or "y=..." and then substituting the rearranged equation into the other equation and so eliminating one variable. 

Specifically for this example it could be:

Rearrange 7x - 2y = 25 to 2y = 7x - 25. Then divide the entire equation by 2, giving: y = (7/2)x - (25/2). 

Now enter this new equation into the second equation in place of y and solve for x: 5x + 3y = 9 becomes 5x+3(3.5x - 12.5) = 9. Rearrange by first expanding the brackets and collecting all x on one side and then dividing by the coefficient of x to give x = 3.

Now enter this into an equation and solve for y. For instance: 5x + 3y = 9, set x=3 giving 5(3) + 3y = 9. 3y=(-6) Y=(-2) 

you can check this but entering both these values for x and y into the second equation for example. 7(3)-2(-2)= 25

21- (-4) = 25. Therefore this is the correct solution. 

Màiri G. A Level German tutor, 13 Plus  German tutor, GCSE German tut...

4 months ago

Answered by Màiri, who has applied to tutor GCSE Maths with MyTutor


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

457 SUBJECT SPECIALISTS

£18 /hr

Rosie P.

Degree: Biological Sciences (Bachelors) - Oxford, The Queen's College University

Subjects offered: Maths, Chemistry+ 3 more

Maths
Chemistry
Biology
-Personal Statements-
-Oxbridge Preparation-

“About Me: I am a Biological Sciences student at Oxford University. I have always had a passion for the sciences and I absolutely love teaching. I believe that with a little bit of help every student is capable of understanding key sci...”

MyTutor guarantee

£18 /hr

Liam P.

Degree: Biological Sciences with integrated masters (Masters) - Durham University

Subjects offered: Maths, Biology

Maths
Biology

“A little bit about me I am currently studying for my masters in Biology at the University of Durham. In the coming year I will be working on modelling the effect of climate change on migratory birds. I found studying bird migration fa...”

MyTutor guarantee

£18 /hr

Michael L.

Degree: Medicinal Chemistry (Masters) - Leeds University

Subjects offered: Maths, Science+ 1 more

Maths
Science
Chemistry

“I am currently in the penultimate year of my Masters degree in Medicinal Chemistry at the University of Leeds. At present, I'm averaging first class marks. Alongside my studies, I am a keen cyclist and am a cycling leader with Leeds R...”

MyTutor guarantee

About the author

£18 /hr

Màiri G.

Degree: Politics and Economics (Bachelors) - York University

Subjects offered: Maths, German

Maths
German

“Hi, my name is Màiri and I am currently studying Politics and Economics at York University. I've lived in Germany my entire life as my mum is German but due to my dad being British and wanting me to also have an English education, I a...”

MyTutor guarantee

You may also like...

Other GCSE Maths questions

13 - 3 × 4+2 Simple question that lots of people get wrong

Make X the subject of the equation (9x-7)/3 = 8y

How do you find the equation of a straight line on a graph?

The normal price of a television is £1200. It is reduced to £970. Work out the percentage reduction. Give your answer to 1 decimal place.

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