計下下面概數=]
展開(化簡)下面概數
1.(y-2)(y+2)
2.(4+x)(3-2x)
3.(4+x)(5+x)
做到嗎??
(由於打唔到次方,所以只好打多幾次,如x概3次方寫成xxx)
依降冪排的﹕
1.(y-2)(y+2)
=y(y+2)+(-2)(y+2)
=yy+2y-2y-4
=yy-4
2.(4+x)(3-2x)
=4(3-2x)+x(3-2x)
=12-8x+3x-2xx
=-2xx-5x+12
3.(4+x)(5+x)
=4(5+x)+x(5+x)
=20+4x+5x+xx
=xx+9x+20
這是中２最易概多項式相乘
