MYTUTOR SUBJECT ANSWERS

433 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...

11 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

782 SUBJECT SPECIALISTS

£18 /hr

Rhiannon M.

Degree: Environmental Geoscience (Bachelors) - Durham University

Subjects offered:Maths, Geology+ 2 more

Maths
Geology
Geography
Chemistry

“Third year Earth Sciences student at Durham; specialise in geochemistry and tutor in Earth sciences, Chemistry and Maths”

Trusted by schools

|  4 completed tutorials

£18 /hr

Axel R.

Degree: Biochemistry with Management (Bachelors) - Imperial College London University

Subjects offered:Maths, Science+ 2 more

Maths
Science
Chemistry
Biology

“Postgraduate student keen on helping you understand Maths and Science! No matter the level, you CAN succeed!”

MyTutor guarantee

£18 /hr

Heba K.

Degree: Medicine (Bachelors) - University College London University

Subjects offered:Maths, English Literature+ 4 more

Maths
English Literature
Biology
-Personal Statements-
-Medical School Preparation-

“Hello! I'm a 3rd year medical student with a passion for inspiring enthusiasm and making the subjects I tutor fun and easy for my students.”

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

A circle with centre C has equation x^2 + y^2 + 2x - 6y - 40 = 0. Express as (x - a)^2 + (y - b)^2 = d.

Write 3/8 as a decimal

There are three boxes and one has a prize inside. You are told to choose a box. One of the other boxes is then opened, showing that it is empty. You are given the option to switch your choice to the other remaining box. Should you switch? Why?

Rationalise 1/(√7) ?

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