How do you solve the following simultaneous equation?

MYTUTOR SUBJECT ANSWERS

Answers / Maths / GCSE / How do you solve the following simultaneous equation?

759 views

How do you solve the following simultaneous equation?

2x - 6y = 18

4x + 3y = 6

First, make either the x or y the same value by multiplying the equations. Let's choose x.

2x - 6y = 18 x2

4x + 3y = 6 x1

(+)4x - 12y = 36

(+)4x + 3y = 6

Now, we use the rule of 'same sign subtract', 'different sign add'. As the signs are the same in this example, we will subtract the equations.

-15y = 30

Now, we must divide both sides by -15 in order to isolate the y.

y = 30/-15

y = -2

We must then substitute the value for y into one of the equations to find x.

4x + 3y = 6 (substitute y = -2)

4x + 3(-2) = 6

4x - 6 = 6

Now we must add 6 to both sides to get the 4x on its own.

4x = 12

Then divide both sides by 4 to find the value of x.

x = 12/4

x = 3

We can then check our values (x = 3, y = -2) are correct by substituting them into the other equation.

4x + 3y = 6 (substitute x = 3, y = -2)

4(3) + 3(-2) = 6

12 - 6 = 6

6 = 6

This means that we successfully solved the simultaneous equation.

Jason E. A Level Business Studies tutor, GCSE Business Studies tutor,...

2 years ago

Answered by Jason, a GCSE Maths tutor with MyTutor

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

615 SUBJECT SPECIALISTS

Guido B. 11 Plus Maths tutor, GCSE Maths tutor, 13 Plus Maths tutor,...

View profile

£18 /hr

Guido B.

Degree: Aeronautical Engineering (Masters) - Imperial College London University

Subjects offered:Maths, Science+ 3 more

“Expert tuition from an expert. A second year Uni student who's completed the hassle of GCSEs and A Levels, and can teach you the easy way to pass and succeed!”