Factorise the following using the identity ${\mathrm{a}}^2-{\mathrm{b}}^2=(\mathrm{a}+\mathrm{b})(\mathrm{a}-\mathrm{b})$

${\mathrm{a}}^4-(\mathrm{a}-\mathrm{b}{)}^4$

Factorise the following using the identity ${\mathrm{a}}^2-{\mathrm{b}}^2=(\mathrm{a}+\mathrm{b})(\mathrm{a}-\mathrm{b})$

${\mathrm{x}}^4-1$

Factorise the following using the identity ${\mathrm{a}}^2-{\mathrm{b}}^2=(\mathrm{a}+\mathrm{b})(\mathrm{a}-\mathrm{b})$

${\mathrm{y}}^4-625$

Factorise the following using the identity ${\mathrm{a}}^2-{\mathrm{b}}^2=(\mathrm{a}+\mathrm{b})(\mathrm{a}-\mathrm{b})$

${\mathrm{p}}^5-16\mathrm{p}$

Factorise the following using the identity ${\mathrm{a}}^2-{\mathrm{b}}^2=(\mathrm{a}+\mathrm{b})(\mathrm{a}-\mathrm{b})$

$16{\mathrm{x}}^4-81$

Factorise the following using the identity ${\mathrm{a}}^2-{\mathrm{b}}^2=(\mathrm{a}+\mathrm{b})(\mathrm{a}-\mathrm{b})$

${\mathrm{x}}^4-{\mathrm{y}}^4$

Factorise the following using the identity ${\mathrm{a}}^2-{\mathrm{b}}^2=(\mathrm{a}+\mathrm{b})(\mathrm{a}-\mathrm{b})$

${\mathrm{y}}^4-81$

Factorise the following using the identity ${\mathrm{a}}^2-{\mathrm{b}}^2=(\mathrm{a}+\mathrm{b})(\mathrm{a}-\mathrm{b})$

$16{\mathrm{x}}^4-625{\mathrm{y}}^4$

Factorise the following using the identity ${\mathrm{a}}^2-{\mathrm{b}}^2=(\mathrm{a}+\mathrm{b})(\mathrm{a}-\mathrm{b})$

$(\mathrm{a}-\mathrm{b}{)}^2-(\mathrm{b}-\mathrm{c}{)}^2$