x + y = 11, and x^2 + y^2 = 61, Work out values of y in the form of x
This is a simultaneous equation question, and it is important to read the question and pick out the information we want, and see what we are trying to get to, then work out a pathway on how we will get to it:we are give 1) x + y = 11, and 2) x2 + y2 = 61so we can rearrange equation 1 so it is x = 11- y, the substitute this into equation 2.so we then get (11-y)2 + y2 = 61, all you did was replace x2 in equation 2 because we found out what x was by rearranging equation 1. Now you expand the brackets to get (121 - 22y + y2) + y2 = 61which is 2y2 -22y + 121 = 61, then you minus 61 on both sides so your equation is equal to 0,2y2 -22y + 60 = 0 so y =√(11x−30) or y=−√(11x−30) (you will get +/- as it a root)
