Find the value of `x^2-y^2+1/(2!)(x^4-y^4)+1/(3!)(x^6-y^6)+…`

Explanation

`x^2-y^2+1/(2!)(x^4-y^4)+1/(3!)(x^6-y^6)+...=(x^2+(x^2)^2/(2!)+(x^3)^3/(3!)+....)-(y^2+(y^2)^2/(2!)+(y^3)^3/(3!)+...)=(e^(x^2)-1)-(e^(y^2)-1)=e^(x^2)-e^(y^2)`