5x+15x=( + ) x=20x 5ab-2ab+ab=( - + )ab=(

问题描述:

5x+15x=( + ) x=20x 5ab-2ab+ab=( - + )ab=(

(5+15)
(5-2+1)
(4ab)

5x+15x=(5+15 ) x=20x 5ab-2ab+ab=( 5-2 +1 )ab=(4ab )急呀!!!

5x+15x=(5 +15 ) x=20x
5ab-2ab+ab=( 5- 2+1 )ab=( 4ab)