Question

subtract a^2 - b^2 from b^2-a^2

Answer 1

b^2-a^2-(a^2-b^2)=2(b^2-a^2)

Answer 2

$(b {}^{2} - a {}^{2} ) - (a {}^{2} - b {}^{2} ) \\ = b {}^{2} - a {}^{2} - a {}^{2} + b {}^{2} \\ = b {}^{2} + b {}^{2} - a {}^{2} - a {}^{2} \\ = 2 b {}^{2} - 2a {}^{2} \\ = 2(b {}^{2} - a {}^{2} )$