Solve the two simultaneous equations X2 +2Y2= 18 and X - Y = 3

1) X² +2Y²= 182) X - Y = 3
Rearrange 2) in the form X=3-Y then substitute in to 1); (3-y)²+2Y²=18, this is your new equation 39+3Y+3Y+Y²+2Y²=183) 9+6y+3Y²= 18Divide equation 3) by 33 +2Y+Y²=6Solve for Y by equating to zero then factorising in to double brackets;Y²+2Y -3 = 0(Y+3)(Y-1)=0when (Y-1)=0, Y =1 and when (Y+3)=0, Y=-3solve x by substituting your found Y values in to equation 2when Y=1; X-1 = 3 so X=4When Y=-3; X--3=3, so X=0