Answer:
[tex]\large\boxed{LCM(121x^2-9y^2,\ 11x^2+3xy)=121x^3-9xy^2}[/tex]
Step-by-step explanation:
[tex]121x^2-9y^2=11^2x^2-3^2y^2=(11x)^2-(3y)^2\\\\\text{use}\ a^2-b^2=(a-b)(a+b)\\\\=(11x-3y)\underline{(11x+3y)}\\\\11x^2+3yx=x\underline{(11x+3y)}\\\\LCM(121x^2-8y^2,\ 11x^2+3yx)=\underline{(11x+3y)}(11x-3y)(x)\\\\=(121x^2-9y^2)(x)=121x^3-9xy^2[/tex]