How do i solve simultaneous equations?

simulatneous equations are solved by eliminating one of the unknowns such as x or y. there are a number of ways to do this such as substitution or subtraction/addition. For this example we will use subtraction addition as i always found that the easier method at GCSE since it often avoids fractions.e.g. 2y=3x+12 and 3y=5x+14we need to choose one of the two unknowns to eliminate and then find their lowest common denominator. I will choose x, where the LCD is 15 (35=15). now we multiply the entire equation through in order that the number in front of x (called the coefficient) is 15. in the first equation, we multiply through by 5.(25)y=(35)x+(125)10y=15x+60in the second equation we multiply through by 3 like before(33)y=(53)x+(143)9y=15x+42now both the coefficients of x are 15 so we can subtract one equation from the other(10-9)y=(15-15)x+(60-42)y=0x+18y=18we now have the y value, since x is now zero. to find the x value all we need to do is go back to one of the first equations and put the value y=18 into the equation to resolve for x.(218)=3x+1236-12=3x24=3xx=8and thats everything. By making sure we can subtract one equation from another to eliminate one of the unkowns we can subsequently obtain both values. in this case, y=18 and x=8 

Answered by Matthew K. Maths tutor

4814 Views

See similar Maths GCSE tutors

Related Maths GCSE answers

All answers ▸

How can I find x and y?


Write 2x^2 + 6x + 6 in the form a(x^2 + b) + c by completing the square.


make a the subject of p = (3a+5)/(4-a)


Tom starts with 50 balls. Amy starts with 28 balls. If Tom gives 22 balls to Amy, what percentage of balls does Tom have compared with Amy?


We're here to help

contact us iconContact usWhatsapp logoMessage us on Whatsapptelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

© MyTutorWeb Ltd 2013–2025

Terms & Conditions|Privacy Policy
Cookie Preferences