⑴3x²＋5x－8
=3x²－3x＋8x－8
=3x﹙x－1﹚＋8﹙x－1﹚
=﹙x－1﹚﹙3x＋8﹚.
⑵x²﹙x²＋2y²﹚－3y^4
=x^4＋2x²y²－3y^4
=﹙x²﹚²－x²y²＋3x²y²－3﹙y²﹚²
=x²﹙x²－y²﹚＋3y²﹙x²－y²﹚
=﹙x²－y²﹚﹙x²＋3y²﹚
=﹙x＋y﹚﹙x－y﹚﹙x²＋3y²﹚.
⑶－6x²＋12－x
=－﹙6x²＋x－12﹚
=－﹙2x＋3﹚﹙3x－4﹚
⑷6x²－7x＋2
=6x²－3x－4x＋2
=3x﹙2x－1﹚－2﹙2x－1﹚
=﹙2x－1﹚﹙3x－2﹚.