5.4 应用一元一次方程——打折销售 课件 2023--2024学年北师大版七年级数学上册

初中数学七年级(上) 应用一元一次方程 ——打折销售 1.理解商品销售中所涉及进价、原价、售价、利润、打折、利润率这些基本量之间关系。 2.能在具体打折销售问题中准确找出等量关系列方程求解。 学习目标 ······································································································ 问题：打折销售问题中有哪些量?这些量之间有何关系? 成本价(进价)： 标价(原价)： 销售价： 利润： 利润率： 知识回顾 有时也称进价，是商家进货时的价格 消费者购买时真正花的钱数. 商家在出售时，标注的价格. 商家在销售商品后的纯收入. 利润占进价的百分率 折扣： 商家为了促销所采用的一种手段. ······································································································ 利润率= 进价 利润 ×100% 售价＝ 标价× 折扣数 10 进价 售价= ×(1+利润率) 打 折 销 售 利润 = 售价—进价 利润 =进价×利润率 ······································································································ 知识回顾 1.原价100元的商品打8折后价格为____元，x折是 元； 2.原价100元的商品提价40%后的价格为 元； 3.进价100元的商品以150元卖出，利润是____元，利润率是______； 4.用100元购进的商品，利润率为20%，则利润为 元，售价为 ______元. 80 10x 140 50 50% 20 120 知识回顾 ······································································································ ······································································································ 例1：一家商店将某种服装按成本价提高40%后标价，又以8折优惠卖出，结果每件仍获利15元，这种服装每件的成本是多少元？ 例题讲解 ······································································································ 思考 设每件服装的成本价为 x 元，你能用含 x 的代数式表示其他的量吗？问题中有怎样的等量关系？ 每件衣服标价为_________________________； （1+40%）x 元 每件衣服的实际售价为___________________； （1+40%）·x·80% 元 每件衣服的利润为_______________________； [（1+40%）·x·80%－x] 元 利润=实际售价－成本价=15元 由此，列出方程_________________________； （1+40%）·x·80%－x=15 解方程，得 x =__________________________. 因此每件服装的成本______元. 125 125 等量关系：__________________________; 解：设每件衣服的成本价为x元，那么 列出方程 . 答：这种服装每件的成本价是 元． 解方程，得 . x (1＋40%)x (1＋40%)x·80% (1＋40%)x·80%－x 15 (1＋40%)x·80%－x＝15 x＝125 125 ······································································································ = 例2 某商场将某种商品按原价的8折出售，此时商品的利润率是10％，已知这种商品的进价为1800元，那么这种商品的原价是多少？ 分析