Question

分解因式 81a的四次方-16b的四次方

Answer 1

81a的四次方-16b的四次方

=(9a^2)^2-(4b^2)^2

=(9a^2+4b^2)(9a^2-4b^2)

=(9a^2+4b^2)(3a+2b)(3a-2b)