If x^2 + y^2 = 20 and y=10 - 2x, find x and y.
First work out y2 using the second equation, making sure to do this using the FOIL technique. Then substitute this into the first equation to get 5x2 - 40x - 80 = 0. All the terms in this can be divided by 5 to get x2 - 8x +16=0. Then factorise this to get (x-4)2=0. Therefore, x=4. Putting this value of x into the second equation gets the result of y=2
ST
Related Maths GCSE answers
All answers ▸Find the roots of the quadratic equation, x^2 - 8x + 24 = 0, by completing the square.
John ran a 450m race (2sf) in a time of 62 seconds (nearest second). Calculate the difference between his maximum and minimum average speed. (3sf)
When do two simultaneous equations have a solution?
Differentiate the following: 5x^3 + 4x^2 + 3x + 2