Find the derivative of the function.y= 2^3 -x^2

cant get the right answer, i think its partly due to me not knowing the derivative of 2^x.

I did:

outside function = 2^x

outside deriv.= 2^xlog(2) <----this is what i got from an online deriv. calc

inside = 3-x^2

inside deriv = -2x

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