Factorise $x^2-8x+16$, using suitable identity.

Factorise $y^2+20y+100$, using suitable identity.

Factorise $36m^2+60m+25$, using suitable identity.

Factorise $64x^2-112xy+49y^2$, using suitable identity.

Factorise $a^2+6ab+9b^2-c^2$, using suitable identity.