 Hello and welcome to the session. In this session we discussed the following question which says if x-y is equal to 7 and x-y is equal to 9, find the value of x-square plus y-square. Before moving on to the solution, let's recall the identity. a-b whole square is equal to a-square minus 2ab plus b-square. We take this as the key idea to be used in this question. Now let's move on to the solution. We are given x-y as 7, x-y as 9 and we need to find the value for x-square plus y-square. Now in the identity a-b whole square is equal to a-square minus 2ab plus b-square. We take a as x and b as y. So we get x-y whole square is equal to x-square minus 2xy plus y-square. Next we put the value for x-y as 7 and x-y as 9. So this gives us 7 whole square is equal to x-square minus 2 into 9 plus y-square. So this further gives us 49 is equal to x-square minus 18 plus y-square. Now from here we get x-square plus y-square is equal to 49 plus 18. This gives us x-square plus y-square is equal to 67. So we have the value for x-square plus y-square is 67. Our final answer is 67. So this completes the session. Hope you have understood the solution for this question.