A Level maths students, can you help answer these two questions please?

I'm really stuck on these two questions and would appreciate it very much if I could get some help.

1) Solve this algebraically:
x + y = 9
x^2 - 3xy + 2y^2 = 0

2) Solve this: (leave your answer as a surd)
16x^4 - 4x^2 = 25

An explained answer would be amazing, as I want to learn the technique. Thank you very much!

Reply 1

Kevin De Bruyne

Original post by Student150

1. What different ways do you know to solve simultaneous equations? Which one seems most sensible to apply here?

2. What different ways can you solve a quadratic equation? Which one seems most sensible to apply here?

Reply 2

NadeemKha_Arab

I'm not sure what stage of education you are at so i'll give you a chance to answer them anyway., However I will point you in the right direction.

1) This is a simulateaneous question. So you need to rearrange one of the equations and sub it into the other. That way you will get a value(s) for one letter and then sub your answer in again to get your answer for the other letter.

2) I hope you can appreciate this has a similar layout to a quadratic equation - it is a 'disguised quadratic'. I hope that helps.

If you need more info then let me know, but please try it first.