Solve the simultaneous equations: 5x+y=21, x-3y=9

Step 1. Take one equation and make either x or y the subject of the formulax=9+3y, 5x+y=21Step 2. Substitute in the equation5(9+3y)+y=21Step 3. Make y the subject of the formula45+15y+y=21 (multiplied out the brackets)16y=-24 (Subtracted 45 from both sides)y=-24/16 (Divided by 16 on both sides)y=-3/2 (Scaled the fraction down) Step 4. Find out what x is equal tox=9+3(-3/2)x=4.5 or 9/2

Answered by marcus J. Maths tutor

2291 Views

See similar Maths GCSE tutors

Related Maths GCSE answers

All answers ▸

Solve the simultaneous equations (1) 2a - 5b = 11 (2) 3a + 2b = 7


Write √ 45 in the form a √ 5, where a is an integer.


(2x + 3y)^2 – (2x – 3y)^2 = 360 show that xy is a multiple of 5


Given that y r 1 2 x , complete this table of values. x 1 2 5 10 y 1


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 2013–2024

Terms & Conditions|Privacy Policy
Cookie Preferences