[tex]36x^{18}+60x^9y^2+25y^4=6^2x^{9\cdot2}+2\cdot6x^9\cdot5y^2+5^2y^{2\cdot2}\\\\=6^2(x^9)^2+2\cdot6x^9\cdot5y^2+5^2(y^2)^2\qquad(*)\\\\=(6x^9)^2+2\cdot6x^9\cdot5y^2+(5y^2)^2\qquad(**)\\\\=(6x^9+5y^2)^2=(6x^2+5y^2)(6x^9+5y^2)\\\\Used:\\\\(*)\qquad(a^n)^m=a^{nm}\\\\(**)\qquad(a+b)^2=a^2+2ab+b^2[/tex]
