Question

factorise the following expressions:x^2-1-2y-y^2

Answer 1

it an imaginary polynomial

Answer 2

${x}^{2} - 1 - 2y - {y}^{2} \\ {x}^{2} - ( {y}^{2} + 2y + 1) \\ {x }^{2} - ( {y}^{} + 1)^{2}$
Now,
${x - (y + 1)}{x + (y + 1)$
$(x - y - 1)(x + y + 1)$