[tex]GCF(64x^3, -24x^4) = GCF(64, -24) GCF(x^3, x^4) = GCF(8\cdot 8, -8 \cdot 3)\ x^3 = 8x^3[/tex]
[tex]GCF(172ac^2,86bc) = GCF(2(86)ac^2,86bc^4) =86a^0b^0c^2 [/tex]
[tex]GCF(240xyz^4, 700xy^2z) = GCF(20 \cdot 12, 20 \cdot 35) GCF(xyz^4,xy^2z)= 20x^1y^1z^1[/tex]