These questions are fairly challenging and aimed at around grade 8 GCSE maths. They deal with solving quadratic simultaneous equations by substitution, and you’ll need good ‘algebra confidence.’ Please do stop the video, try the questions and compare your solution.
Video one – solve:
x – 2x = 3
x² + y² = 18
Video two – solve:
x – 2y = 1
x² + y² = 13
The whole idea is to make ‘x’ the subject, and ‘substitute’ into the circle equation to find values of x and y that are the same for both equations. With some questions you might need to make ‘y’ the subject, but the same principles apply.
The problems are aimed at around grade 8, and the topic appears in all the main examination boards, including Edexcel, AQA and OCR. There are other ‘linear’ simultaneous equations, that might be a little easier, and here’s a post that might be of interest. Please note that this would be around grade 6:
Additionally, here’s some other posts that might be of interest:
I hope the videos on quadratic simultaneous equations by substitution help, and please leave a comment below, if you are not sure. Alternately you can view my YouTube channel and leave a comment there – I’ll always try to respond as quickly as possible.
Watch the videos on YouTube: