因式分解：4/9x^2-2x+9/4

4/9x^2-2x+9/4
=(2／3x)²－2×2／3×3／2x＋(3／2)²
=(2／3x－3／2)²
=[1／6(4x－9)]²
=1／36(4x－9)²
(3m+n)(2m-n)-(m+3n)(n-2m)
=(3m+n)(2m-n)＋(m＋3n)(2m－n)
=(2m－n)(3m＋n＋m＋3n)
=(2m－n)(4m＋4n)
=4(2m－n)(m＋n)
5(x-y)^2+7(x-y)-6
=[5(x－y)－3](x－y＋2)
=(5x－5y－3)(x－y＋2)
十字相乘
5(x－y) ﹣3
x－y 2