AMC 8 2022 Problem 2

AMC8 2022 年第 2 题

表达式与运算★☆☆☆☆
Consider these two operations as shown below. What is the value of (5 ⧫ 3) ★ 6(5 \, \blacklozenge \, 3) \, \bigstar \, 6?
考虑下图所示的两种运算。那么 (5 ⧫ 3) ★ 6(5 \, \blacklozenge \, 3) \, \bigstar \, 6 的值是多少?
AMC 8 2022 Problem 2 figure
  1. A.{-}20
  2. B.4
  3. C.16
  4. D.100
  5. E.220

正确答案 · Correct Answer

D

解析 · Solution

Solution 1

We can find a general solution to any ((a ⧫ b) ★ c)((a \, \blacklozenge \, b) \, \bigstar \, c). ((a ⧫ b) ★ c)((a \, \blacklozenge \, b) \, \bigstar \, c) =((a2−b2) ★ c)=((a^2-b^2) \, \bigstar \, c) =(a2−b2−c)2=(a^2-b^2-c)^2 =a4+b4−(a2)(b2)−2(a2)(c)−(b2)(a2)+2(b2)(c)+c2=a^4+b^4-(a^2)(b^2)-2(a^2)(c)-(b^2)(a^2)+2(b^2)(c)+c^2 =54+34−(52)(32)−2(52)(6)−(32)(52)+2(32)(6)+62=5^4+3^4-(5^2)(3^2)-2(5^2)(6)-(3^2)(5^2)+2(3^2)(6)+6^2 =625+81-225-300-225+108+36 =100 "This is very time wasting" There are unnecessary equations ':( solution 2 guys To time wasting just go to solution 2

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