将变量转换为数字，第i部分

在这一集中，我将向您介绍转向变量的策略，可能是SAT数学部分最重要的策略。所以倾听，如果你想重新审视这一集，直到你真的，真的很沮丧，我强烈推荐它。现在，将变量转换为数字将使许多数学问题更容易。这不仅仅是每个测试的一两个，它是几个部分，所以你可以用很多频率，另外，策略很棒，因为它适用于每个人。如果你是一个总数学摇滚明星，它将产生最困难的问题，只有中等困难，如果你真的挣扎着数学，那将使中等困难的问题变得易于到媒体，所以它有助于董事会和战略有用三个基本步骤。首先，您将要将数字分配给变量，所以无论什么是变量，您将要成为一个数字。下一步，您将使用您选择的这些数字来解决您的问题，然后是最后，简化与您提出的解决方案匹配的答案选择。让我们在很多细节中查看这三个步骤，用例子的音调更详细。
所以,我要向您展示几个例子我们将变量转化为数字,如果你能做到这些问题使用“真实”的数学很好,但是,我想让你练习以下步骤,因为你需要习惯,有时容易问题为了流利当你真正要解决困难的问题。所以，即使你可以用正确的方法来做这件事，我也希望你能理解这个策略，并能够应用它。
让我们从这个问题开始;w和x的平均值或算术平均值是六个，y和z的平均值是10. w，x，y和x的平均值是多少？因此，第一步是将我们的变量转化为数字，我应该通常希望避免第一个和两个，您通常希望避免重复数字。所以，例如，让我们看看，我需要选择两个值的两个值，但如果可能，我应该避免一个和两个，我不应该重复它们，他们需要平均到六个。所以，我可以使用各种各样的数字，但是让我们尝试五个和七，因为我知道五个平均六个平均值，然后也是y和z的平均值。再次，我可以选择的数字音调，但我会保持简单，并说九个和11，因为那些平均到10。所以我已经完成了将它们转化为数字的那一点，我已经准备好了第二步;使用我选择的数字来解决方程。所以，问题是，W，X，Y和Z的平均值是多少。所以，W和x和y和z的平均值是什么，所以我将它们添加到四个，因为这是平均值和计算器可能有所帮助的，但答案结果是八个。 So that's pretty easy. I'm ready for step three which is just finding the match. I got eight, c is eight. The answer is c.
让我们看另一个例子。如果a, b, c和d连续偶数和“a”小于“b”小于“c”小于“d”那么b + d大于a + c多少。所以,我先将这些变量转化为数字,必须遵守任何限制的问题。我被告知a b c d是连续的偶数，这意味着偶数的顺序是2 4 6 8 10等等我被告知a是最小的，一直到d。所以，我要继续赋值2,4,6,8我必须保持它们的顺序因为它说2a是最小的它从这里开始。我想我已经完成了第一步，也就是赋值。准备好第二步，也就是回答问题。问题是b + d比a + c大多少?我们来算一下，b + d等于b是多少?B是4 d是8，结果是12比a + c大多少，a是多少?我们确定a是2 c是6，结果是8。 So the question is, this is how much greater than this and the answer is that's it's four greater so that's the answer. Now that we've gotten the answer to the question we're ready for the final step which is go find the answer choice that matches. We said it's four greater and that's b.
让我们看一下另一个例子;'在一系列正整数中的第一项之后，每个术语与紧接在其之前的术语的比率是三到一个。第五个术语与第二项的比率是多少？“所以，我要指出的一件事就是这可能会提醒你两章的代数两章，这可能会派上用场，但是很多人所做的就是他们看到这个，他们说，“我不记得公式，我不能这样做。我最好放弃。“但是，如果你只是读过他们，那么仔细阅读它们，那么你会没事的，在这里也是如此。我们不会使用一个疯狂的奇特公式，只是思考它，所以这是我想弄清楚这个问题的一点。我想做的另一点是如果没有变量，它会发现它有点隐藏在问题中。他们谈论第一个术语，然后谈论另一个术语，所以隐藏变量是第一个术语，我们可以通过我们想要的一项是我们的变量来实现第一任期。所以让我们从数字开始以保持简单。第一个术语让我们成为一个，然后模式是每个术语与紧接在其之前的术语的比率是三到一个。 Ratio means there's a multiplication so the second term it's going to be multiplied by three. The third term it's going to be multiplied by three again so that's nine, the fourth term is going to be multiplied by three again so that's 27. The fifth term is going to be multiplied by three again so that's 81, so I think we've gotten enough progress here on picking our numbers and we're ready to actually answer the question. What's the ratio of the fifth term to the second term?
所以我们正在处理这个术语和这个词。什么是81到三个的比率？所以这是答案，但正如你所看到的那样，它不会减少，所以它与答案选择不匹配，这是我们最终第三步的答案选择。因此，如果我们将这两个划分为三个，它将变为27到一个，并且确定足够的时间，最后一步是找到匹配，我们的比赛是d。另一个例子的时间。“如果10％等于y和40％的w等于z，则z的百分比是y？'好的，这个有点难得让我们看看这里。例如，某些数字比其他人更有意义，例如，我注意到我们注意到我们在这里的10％的“W”和40％的人在这里和很多时候在处理百分之症时，合适的工作是件好事像100的数字一样。占100％的百分比。如果我要求你占11.54的10％，除非你有点是那件事，否则它不会那么有趣。好吧，所以让我们说W是100，这将相对容易地工作。 So 10 percent of w, 10 percent of 100 is y, what's 10 percent of 100? Well, hopefully you know it's ten but if not, your calculator could help you with that and since that's 10 and it's y we'll write it there so we don't lose track and then 40 percent of w, 40 percent of that same 100 equals z, what's 40 percent of 100? It's 40. Now I should point out here that since w appears twice, it has to be the same number both times. You don't get to make up different numbers as you work through the problem. So we finished assigning numbers and we're ready to answer the question, the second step. What percent of z is y? What percent of... let's see, z is 40 and y is 10, so the question is, what percent of 40 is 10 or in other words 10 is what percent of 40? Now there are many ways to solve this but it's basically asking as a percentage, 10 is what compared to 40? Well, it's one fourth and you can ask your calculator if you need to but maybe you remember that one fourth is 25 percent. So we've got our answer and then step three is just to look for the answer right there, b, 25 percent.
另一个例子，'如果m被除两个，则其余部分为零。如果4米+ 1分为两个，则剩余时间是多少？现在，这有点不同。之前，当我们挑选数字时，我们不得不遵循的规则是有点明显的。这个人更加定居。我们提前不太了解是什么M是，我们必须在我们找到M的零点划分时播放之前，给出零的剩余时间。例如，如果我们要尝试第三号，那就不起作用，让我告诉你。当数字M分为两个时，其余时间为零。好吧，让我们试试这个。两次进入三次，减去了这两个，你得到一个。 So, three divided by two is one with a remainder of one and that violates the requirement. Our requirement is the remainder zero, this is not for that requirement. So that value of three for m is not going to work. Now, you could play around a little bit but one value that would work is four and I'll just demonstrate for you, so you feel comfortable with that. When four is divided by two, it goes in two times, two times two is four, subtract it and that's your remainder of zero. So sure enough in choosing a value of four for 'm' we've met the rules stated in the equation or rather stated in the question and now we're ready to actually answer the question being asked. What is the remainder if 4m + 1 is divided by two? So let's see 4m +1, what is that? Well we decided that m was four, so four m plus one is four times four, that's 16 plus one that's 17. So the question is, what's the remainder when 17 is divided by two? Let's do that. Not too complicated, divided by two. Eight times two is 16, subtract and it's eight remainder one. So the question is what's the remainder and the answer is one. Now we go look for our answer here and there it is, b.
最后一个例子。如果y = 4乘以x³，当x翻倍时y的值会发生什么这和我们之前见过的问题有点不同因为它们是前后的问题。x有一个初始值，这使得y根据方程是一个确定的值然后x被翻倍，结果y又变了。这是原来的情况和新的情况。让我们做一个前后对比。让我们试试x = 3。在我们得到x = 3 y = 4 * x = 3³之前。3的立方是27 27乘以4正好是108，这是y的初始值，现在我们在x已经翻倍的情况下重复它。所以它不再是3，而是6的两倍，我们再次进行数学运算。 Four times the new value of x which is six also cubed and we go through all this Math it's pretty complicated, we get 864. Now we're ready to answer the question, what happens to the value of y when x is doubled? So y went from being 108 to 864 and the answer is, it got multiplied by eight. It would be really easy to verify that by dividing this by this that would give you a result of eight, it's eight times as big. So it's step three which is basically nothing at all. Let's just say, oh, hey, look! That's the answer choice E, y has now been multiplied by eight. So let's tie together everything we've covered with these examples here.
因此回顾，将变量转换为数字有三个基本步骤，可能需要一段时间才能习惯，但它绝对值得您投资这种策略的时间流利。所以首先，你要将数字分配给变量。当你这样做时，尝试避免一个和两个，尝试不要重复不同变量的数字，也试图选择适合规则的数字，因此如果问题说两个数字乘以另一个数字，请确保该语句是真的。如果您被告知该号码即使是连续的，请确保它等等。下一步，一旦你有那些号码，使用这些数字来解决问题，最后找到答案选择非常简单地与您确定的答案匹配，并且将变量转换为数字。