Factorise:
a4−343a
We know a3−b3=(a−b)(a2+ab+b2)a4−343a=a(a3−343)=a(a3−73)=a[(a−7)(a2+7a+72)]=a[(a−7)(a2+7a+49)]=a(a−7)(a2+7a+49)
a4−1