AMC 8 2016 Problem 10
AMC8 2016 年第 10 题
表达式与运算★★☆☆☆
Suppose that a * b means 3a-b. What is the value of if
假设 a * b 表示 3a-b。若 2 * (5 * x) = 1，那么 的值是多少？
- A.
- B.2
- C.
- D.10
- E.14.
正确答案 · Correct Answer
D
解析 · Solution
Solution 1
Let us plug in (5 * x)=1 into 3a-b. Thus it would be 3(5)-x. Now we have 2*(15-x)=1. Plugging 2*(15-x) into 3a-b, we have 6-15+x=1. Solving for we have -9+x=1 x=10
Let us set a variable equal to 5 * x. Solving for y in the equation 3(2)-y=1, we see that y is equal to five. By substitution, we see that 5 * x = 5. Solving for x in the equation 5(3)-x = 5 we get x=10
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