b^7x-bx^7 = bx(b^6 - x^6) = bx((b^3)^2 - (x^3)^2) = bx(b^3 - x^3)(b^3 + x^3) = bx(b +x)(b - x)(b^2 - bx + x^2)(b^2 + bx + x^2)
b^7x-bx^7 = bx(b^6 - x^6) = bx((b^3)^2 - (x^3)^2) = bx(b^3 - x^3)(b^3 + x^3) = bx(b +x)(b - x)(b^2 - bx + x^2)(b^2 + bx + x^2)