Math CentralQuandaries & Queries


Question from Xiu, a student:

I dont get this question..
Write "the cube of -2y" in exponential form. I know the answer is -(2y)^2 but i really dont understand why. Can you explain how to do this whole problem for me?

Hi Xiu,

The "cube" of an expression must be raised to the third power, not the second as you have written.

"The cube of -2y" means, mathematically, to multiply "-2y" with itself 3 times: (-2y)(-2y)(-2y)
In exponential form this is equal to (-2y)3 which is equivalent to -(2y)3 or -8y3

Hope this helps,

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