Mathematics revision

Factorise

 $10\left(p-2q\right)^3\ +6\left(p-2q\right)^2\ -20\left(p-2q\right)$  

Factorise

 $x^3-x^2+ax+x-a-1$  

Factorise

 $x^3-3x^2-x+3$  

Factorise

 $1-\left(b-c\right)^2$  

Evaluate by using factors

 $\left(979\right)^2-\left(21\right)^2$  

Factorise

 $84-2r-2r^2$  

Factorise

 $8\left(a-2b\right)^2-2a+4b-1$  

Factorise

 $9x^2-\left(x^2-4\right)^2$