①1/3（m²-9n²）=1/3(m+3n)(m-3n)②ab(a⁴-1)=ab(a²+1)(a²-1)=ab(a²+1)(a+1)(a-1)③(m+n)(a⁴-b⁴)=(m+n)(a²+b²)(a²-b²)=(m+n)(a²+b²)(a+b)...（x-y）²-9x²=（x-y+3x）(x-y-3x)=(4x-y)(-2x-y)
⑥(

p+2q)(p+3q)+(p+3q)=(p+2q+1)(p+3q)
解释解释，ok？