Question

三個(gè)植樹(shù)隊(duì)共植樹(shù)1800棵，甲隊(duì)植樹(shù)的棵數(shù)是乙隊(duì)的2倍，乙隊(duì)植樹(shù)的棵數(shù)比丙隊(duì)少200棵，三隊(duì)各植樹(shù)多少棵？

Answer 1

分析：由“三個(gè)植樹(shù)隊(duì)共植樹(shù)1800棵”，得出等量關(guān)系式：甲隊(duì)植樹(shù)的棵數(shù)+乙隊(duì)植樹(shù)的棵數(shù)+丙隊(duì)植樹(shù)的棵數(shù)=1800，設(shè)出乙隊(duì)植數(shù)x棵，則甲隊(duì)植樹(shù)2x棵，丙隊(duì)植樹(shù)（x+200）棵，據(jù)此列出方程并解方程即可．

解答：解：設(shè)出乙隊(duì)植數(shù)x棵，則甲隊(duì)植樹(shù)2x棵，丙隊(duì)植樹(shù)（x+200）棵，由題意得：
2x+x+x+200=1800，
        4x=1800-200，
        4x=1600，
         x=1600÷4，
         x=400；
甲隊(duì)植樹(shù)：400×2=800（棵）；
丙隊(duì)植樹(shù)：400+200=600（棵）．
答：甲隊(duì)植樹(shù)800棵，乙隊(duì)植樹(shù)400棵，丙隊(duì)植樹(shù)600棵．

點(diǎn)評(píng)：此題屬于含有三個(gè)未知數(shù)的應(yīng)用題，這類題用方程解答比較容易，關(guān)鍵是找準(zhǔn)數(shù)量間的相等關(guān)系，設(shè)一個(gè)未知數(shù)為x，另2個(gè)未知數(shù)用含x的式子來(lái)表示，進(jìn)而列方程解答即可．