分解因式①4m^2-n^2-2m-n②3x^2y－2x^2＋12xy－8x③2x^2－5x－ax＋3a－3④5x^3－2x^2y＋8y－20x

Question

分解因式①4m^2 -n^2-2m-n ②3x^2y－2x^2＋12xy－8x ③2x^2－5x－ax＋3a－3
④5x^3－2x^2 y＋8y－20x

Answer 1

①4m^2 -n^2-2m-n
=(2m+n)(2m-n)-(2m+n)
=(2m+n)(2m-n-1)
②3x^2y－2x^2＋12xy－8x
=x²(3y-2)+4x(3y-2)
=x(3y-2)(x+4)
③2x^2－5x－ax＋3a－3
=2x²-5x-3-ax+3a
=(2x+1)(x-3)-a(x-3)
=(x-3)(2x+1-a)
④5x^3－2x^2 y＋8y－20x
=x²(5x-2y)-4(5x-2y)
=(5x-2y)(x²-4）
=(5x-2y)(x+2)(x-2)