學(xué)校去年植樹a棵,今年植樹比去年的2.5倍多8棵.今年植樹________棵,當(dāng)a=300時,今年植樹________棵.
2.5a+8 758
分析:根據(jù)“今年植樹比去年的2.5倍多8棵.”知道今年植樹的棵數(shù)=去年植樹的棵數(shù)×2.5倍+8.由此即可求出今年植樹的棵數(shù),把a(bǔ)=300代入求出的含字母的式子,即可求出今年植樹的棵數(shù).
解答:(1)a×2.5+8,
=2.5a+8(棵),
(2)把a(bǔ)=300代入2.5a+8得,
2.5×300+8,
=750++8,
=758(棵),
故答案為:2.5a+8;758.
點評:關(guān)鍵是找出數(shù)量關(guān)系等式:今年植樹的棵數(shù)=去年植樹的棵數(shù)×2.5倍+8,列式解答即可.