Solve the simultaneous equations: 12x - 4y = 12 and 3x + 2y = 12

Method 1 for solving these equations would be to multiply equation 2 (3x + 2y = 12) by 4 so that the x coefficients are equal, this becomes (12y+8x=48). Then subtract equation 1 from equation 2: (12x+8y=48) subtract (12x - 4y=12) which gives (12y=36), this equation can then by simplified by dividing 36 by the y coefficient to give y=3. This y value can then by substituted into equation 1 to find the value of x: 3x + 2(3)=12 which simplifies to 3x=6, therefore this becomes x=2. Method 2 for solving this equation involves dividing equation 1 by 4 to give (3x-y=3) which can be rearranged to give (y=3x-3) - call this equation 3. Equation 3 can then be substituted into equation 2: 3x+2(4x-3)=12, simplify this to become 9x=18, when simplified further this gives x=2. This x value can be substituted back into equation 3 to give y=3(2)-3, therefore y=3.

Answered by Lucca H. Maths tutor

4234 Views

See similar Maths GCSE tutors

Related Maths GCSE answers

All answers ▸

How to complete the square


Mark buys a computer. A VAT of 10% is added to the price of the computer. He pays £246. What was the original price of the computer before VAT was added?


Bag A contains £7.20 in 20p coins. Bag B contains only 5p coins. The number of coins in bag B is three-quarters of the number of coins in bag A. How much money is in bag B? (in £s)


There are 200 students in Year 10. 110 are boys. There are 250 students in Year 11. 140 are boys. Which year has the greater proportion of boys?


We're here to help

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