2a(a+b)-4a
=2a²+2ab-4a
7×3.2-3×（-3.2）
=7x3.2+3x3.2
=(7+3)x3.2
=32
2.8×8+4.6×8+1.3×16
=2.8x8+4.6x8+2.6x8
=(2.8+4.6+2.6)x8
=10x8
=80
如果本題有什么不明白可以追問,
請點擊下面的【選為滿意回答】按鈕,1.3m(a-2b)-a+2b2.2a(a+b)-4a3.4a(x-y)-(x-y)???????????????????????????????????????