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which quadrant contains no solutions for the the region defi

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which quadrant contains no solutions for the the region defind by 2x+y>4?
A:I
B:II
C:III
D:IV
Lets think about a coordinate grid.
2.It has 4 quadrants.
3.The upper right region is called quadrant I
4.The upper left region is called quadrant II
5.The lower left region is called quadrant III
6.The lower right region is called quadrant IV
7.Now think about the coordinate points in each of the 4 regions.
8.Think,think.if you have this equation:2 x + Y > 4 and you have tell which region of the
coordinate grid WILL NOT give you the (X,Y) coordinate pairs to yield a true statement for
2 x + y > 4
9.Tips:try replacing x and y values using these examples below:
for quadrant I try (2,2)
for quadrant II try ( -1,8)
for quadrant III try (-1,-8)
for quadrant IV try ( 8,2)10.After replacing these coordinate pairs in the inequality of :2X + Y >4
WHAT IS YOUR ANSWER CHOICE NO
2x+y>4 定义的区域在哪一个象限中无解?
A:象限1
B:象限2
C:象限3
D:象限4
(这是一道数学题的解题思路.外国的教学方法和国内可能有些不同,你会觉得提出的方法很麻烦又不确定.按我们的习惯,因为 2x+y>4即 y> -2x+4,那么画出坐标和直线 y = -2x+4,直接判断直线上面部分没有经过的象限.答案就是 C)
让我们考虑一下坐标图:
2.它有4个象限
3.右上角的区域叫象限1
4.左上角的区域叫象限2
5.左下角的区域叫象限3
6.右下角的区域叫象限4
7.接着考虑四个区域的坐标点
8.想,想啊想 .对式子 2x+y>4,究竟那一个区域的坐标 (x,y) 对没办法满足它的正解呢?
9.提示:试一试使用下面的 x,y 值代入:
对象限1,试试 (2,2)
对象限2,试试 (-1,8)
对象限3,试试 (-1,-8)
对象限4,试试 (8,2) (题目是 (8,2)应该有误)
10.把这些坐标对代入不等式:2x + y >4 后,你认为答案该选择哪一个呢?