數學題..因式分解

3(x)(x)-8x-16
=3x^2-8x-16
=(3x+4)(X-4)

3(m+1)(m+1)-8m-24
=3(m+1)(m+1)-8m-8-16
=3(m+1)(m+1)-8(m+1)-16
=(3(m+1)+4)((m+1)-4)
=(3m+3+4)(m+1-4)
=(3m+7)(m-3)