Solve the simultaneous equations x+y=8 and 3x-y=4.

Notice that y has the same coefficient (ignoring the sign) in both equations. So, we will use the elimination method. The elimination method means that we will combine the two equations to eliminate the y variable, allowing us to find the value of x. Then, we will substitute this value of x in order to find y.Since y has opposite signs in the two equations, we will eliminate y by adding the equations. Adding gives (x+y) + (3x-y) = 8 + 4. Simplifying gives us 4x = 12 so x = 3. Now, by substituting x = 3 into x + y = 8 we get that 3 + y = 8 so y = 5. Hence we have solved our simultaneous equations and have that x = 3 and y = 5.

FS
Answered by Fiona S. Maths tutor

5208 Views

See similar Maths GCSE tutors

Related Maths GCSE answers

All answers ▸

3n+2 <= 14 and 6n/(n^2+5) > 1 Find possible values of N


How do I solve simultaneous equations by substitution?


Given that y = 5, solve the following equation for x, 9x - 3y = 97 - 5x


x^2 +y^2 =25, y – 3x = 13 - Simultaneous Equations (June 2017)


We're here to help

contact us iconContact ustelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

MyTutor is part of the IXL family of brands:

© 2025 by IXL Learning