Question

add . . x²-y²-1,y²-1-x²,1-x²-y²​

Answer 1

Answer:

${x }^{2} - {y}^{2} - 1 + {y}^{2} - 1 - {x}^{2} + 1 - {x}^{2} - {y}^{2}$

=x^2-y^2-1