解： (m+2)²-9(m-1)²
=(m+2)²-(3m-3)²
=(m+2+3m-3)(m+2-3m+3)
=(4m-1)(-2m+5)
祝你开心
m²+4m+4-9(m²-2m+1)
=m2+4m+4-9m²+18m-9
= - 8m²+22m-5
= - (8m²-22m+5)
= - (2m-5)(4m-1)
=(m+2)^2-[3(m-1)]^2
=[m+2+3(m-1)][m+2-3(m-1)]
=2m+2
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