在平面直角坐标系中,点A(2, 3)、B(6, 7),线段AB的中点为M。若点P(x, y)满足PM = 5且x + y = 10,则点P的横坐标x的可能值为___。
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题目中给出每扇窗户需要2分钟,总用时24分钟。要求擦了多少扇窗户,可以用总时间除以每扇窗户所需时间:24 ÷ 2 = 12。这是一道简单的一元一次方程应用题,设擦了x扇窗户,则2x = 24,解得x = 12。考查学生将实际问题转化为方程并求解的能力,属于一元一次方程知识点,难度简单。
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[{"id":2144,"content":"某学生在解方程时,将方程 2(x + 3) = 10 的第一步写成了 2x + 3 = 10。这个错误是因为该学生没有正确应用哪一条运算规则?","type":"选择题","subject":"数学","grade":"七年级","stage":"初中","difficulty":"简单","answer":"B","explanation":"原方程为 2(x + 3) = 10,正确去括号应为 2x + 6 = 10。但该学生写成了 2x + 3 = 10,说明他只将 2 与 x 相乘,而忽略了与常数项 3 相乘,违反了去括号时‘括号外的数要与括号内每一项相乘’的分配律规则。因此错误原因是选项 B 所述。","options":[{"id":"A","content":"移项时没有改变符号"},{"id":"B","content":"去括号时没有将括号外的数与括号内的每一项相乘"},{"id":"C","content":"合并同类项时计算错误"},{"id":"D","content":"等式两边没有同时除以同一个数"}]},{"id":519,"content":"在一次环保主题活动中,某学校七年级学生收集了可回收垃圾的重量数据(单位:千克),整理如下表所示。若将数据按从小到大的顺序排列,则中位数是多少?\n\n| 班级 | 垃圾重量(千克) |\n|------|------------------|\n| 七(1)班 | 12 |\n| 七(2)班 | 8 |\n| 七(3)班 | 15 |\n| 七(4)班 | 10 |\n| 七(5)班 | 13 |\n| 七(6)班 | 9 |","type":"选择题","subject":"数学","grade":"初一","stage":"初中","difficulty":"简单","answer":"B","explanation":"首先将所有班级的垃圾重量按从小到大的顺序排列:8, 9, 10, 12, 13, 15。共有6个数据,是偶数个,因此中位数是第3个和第4个数的平均数。第3个数是10,第4个数是12,所以中位数为 (10 + 12) ÷ 2 = 22 ÷ 2 = 11。因此正确答案是B。","options":[{"id":"A","content":"10.5"},{"id":"B","content":"11"},{"id":"C","content":"11.5"},{"id":"D","content":"12"}]},{"id":2147,"content":"某学生在解方程时,将方程 2x + 3 = 7 的两边同时减去3,得到 2x = 4,然后两边同时除以2,得到 x = 2。这一过程主要运用了等式的哪一条基本性质?","type":"选择题","subject":"数学","grade":"七年级","stage":"初中","difficulty":"简单","answer":"D","explanation":"该学生在解题过程中,先两边同时减去3(运用了等式性质1:两边同时减去同一个数,等式仍成立),再两边同时除以2(运用了等式性质2:两边同时除以同一个不为零的数,等式仍成立)。因此,整个过程中综合运用了等式的基本性质,选项D最全面准确。","options":[{"id":"A","content":"等式两边同时加上同一个数,等式仍然成立"},{"id":"B","content":"等式两边同时减去同一个数,等式仍然成立"},{"id":"C","content":"等式两边同时乘或除以同一个不为零的数,等式仍然成立"},{"id":"D","content":"以上三条性质都运用了"}]},{"id":2237,"content":"某学生在数轴上从原点出发,先向右移动5个单位长度,再向左移动8个单位长度,接着又向右移动3个单位长度,最后向左移动6个单位长度。此时该学生所在位置的数与它相反数的和是___。","type":"填空题","subject":"数学","grade":"七年级","stage":"初中","difficulty":"困难","answer":"0","explanation":"该学生从原点0出发,依次进行移动:+5(右移5),-8(左移8),+3(右移3),-6(左移6)。计算最终位置:0 + 5 - 8 + 3 - 6 = -6。设该位置的数为-6,其相反数为6,两者之和为-6 + 6 = 0。根据相反数的性质,任何数与其相反数之和恒为0,因此无论最终位置为何,该和始终为0。本题综合考查数轴上的正负数运算及相反数的概念,需多步推理,难度较高。","options":[]},{"id":5,"content":"二次函数y = x² - 4x + 3的对称轴是?","type":"选择题","subject":"数学","grade":"初三","stage":"初中","difficulty":"中等","answer":"B","explanation":"二次函数y = ax² + bx + c的对称轴为x = -b\/(2a),这里a = 1, b = -4,所以对称轴为x = -(-4)\/(2*1) = 2。","options":[{"id":"A","content":"x = 1"},{"id":"B","content":"x = 2"},{"id":"C","content":"x = 3"},{"id":"D","content":"x = 4"}]},{"id":327,"content":"某学生在平面直角坐标系中描出点 A(2, 3) 和点 B(5, 7),然后他计算了这两点之间的距离。请问他计算出的距离最接近下列哪个数值?","type":"选择题","subject":"数学","grade":"初一","stage":"初中","difficulty":"简单","answer":"B","explanation":"根据平面直角坐标系中两点间距离公式:若两点坐标为 (x₁, y₁) 和 (x₂, y₂),则距离为 √[(x₂ - x₁)² + (y₂ - y₁)²]。将点 A(2, 3) 和点 B(5, 7) 代入公式得:√[(5 - 2)² + (7 - 3)²] = √[3² + 4²] = √[9 + 16] = √25 = 5。因此,两点之间的距离为 5,最接近的选项是 B。","options":[{"id":"A","content":"4"},{"id":"B","content":"5"},{"id":"C","content":"6"},{"id":"D","content":"7"}]},{"id":642,"content":"在一次校园植物观察活动中,某学生记录了5种植物的高度(单位:厘米),分别为12、15、18、15、20。这组数据的中位数是____。","type":"填空题","subject":"数学","grade":"初一","stage":"小学","difficulty":"简单","answer":"15","explanation":"首先将这组数据按从小到大的顺序排列:12、15、15、18、20。由于数据个数为5(奇数个),中位数就是位于中间位置的数,即第3个数。第3个数是15,因此这组数据的中位数是15。本题考查的是数据的收集、整理与描述中的中位数概念,属于七年级数学课程内容。","options":[]},{"id":2485,"content":"如图,在△ABC中,∠C = 90°,AC = 6 cm,BC = 8 cm。若将△ABC绕点C逆时针旋转90°,得到△A'B'C,则点A的对应点A'到点B的距离为多少?","type":"选择题","subject":"数学","grade":"九年级","stage":"初中","difficulty":"简单","answer":"C","explanation":"首先,在Rt△ABC中,由勾股定理可得AB = √(AC² + BC²) = √(6² + 8²) = √(36 + 64) = √100 = 10 cm。将△ABC绕点C逆时针旋转90°后,点A旋转至A',点B旋转至B'。由于旋转不改变图形的形状和大小,且∠ACA' = 90°,因此△ACA'为等腰直角三角形,CA = CA' = 6 cm。同理,CB = CB' = 8 cm,且∠BCB' = 90°。此时,点A'位于点C正上方6 cm处,点B位于点C右侧8 cm处。因此,A'到B的水平距离为8 cm,垂直距离为6 cm,构成一个新的直角三角形,其斜边即为A'B。由勾股定理得:A'B = √(8² + 6²) = √(64 + 36) = √100 = 10 cm。故正确答案为C。","options":[{"id":"A","content":"6 cm"},{"id":"B","content":"8 cm"},{"id":"C","content":"10 cm"},{"id":"D","content":"14 cm"}]},{"id":511,"content":"4题","type":"选择题","subject":"数学","grade":"初一","stage":"小学","difficulty":"简单","answer":"待完善","explanation":"解析待完善","options":[]},{"id":185,"content":"小明去文具店买笔记本,每本笔记本的价格是8元。他买了5本,付给收银员50元。请问他应找回多少钱?","type":"选择题","subject":"数学","grade":"初一","stage":"小学","difficulty":"简单","answer":"A","explanation":"首先计算小明购买5本笔记本的总花费:每本8元,5本就是 8 × 5 = 40 元。他付了50元,所以应找回的钱是 50 - 40 = 10 元。因此正确答案是A。","options":[{"id":"A","content":"10元"},{"id":"B","content":"12元"},{"id":"C","content":"15元"},{"id":"D","content":"18元"}]}]