ACT考试数学必做模拟题及解析（一）

>>2019年ACT考试：ACT考试数学必做模拟题及解析（一）

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3x3·2x2y·4x2y is equivalent to:

A. 9x7y2

B. 9x12y2

C. 24x7y2

D. 24x12y

E. 24x12y2

解析：The correct answer is C. To find an equivalent expression, you can multiply the constants (3·2·4), combine the x term (x3x2x2 → x3+2+2 → x7, because when you have a common base you use the base and add the exponents), and combine the y terms (y·y → y1y1 → y1+1 → y2). The result is 24x7y2.

正确答案选C。常数相乘(3·2·4)，合并x项(x3x2x2 → x3+2+2 → x7) 和y项(y·y → y1y1 → y1+1→ y2)，结果为24x7y2。