An estimate for -^66 is

A. -6
B. -7
C. -8
D. -9

I'm not sure How to do this problem?

If you mean -√66, just think a minute:

√36 = 6
√49 = 7
√64 = 8
√81 = 9

66 is close to 64, so √66 is close to 8

But, you have -√66, so C looks good to me.

Thanks

To estimate -^66, we need to understand that raising a negative number to a positive even power will give us a positive result. So, let's estimate using the given options and eliminate the incorrect ones.

Option A: -6
If we raise -6 to an even power, it will always be positive. So, -^66 cannot be -6.

Option B: -7
Similarly, raising -7 to an even power will also yield a positive result. Therefore, -^66 cannot be -7.

Option C: -8
Raising -8 to an even power will give us a positive value. Hence, -^66 cannot be -8.

Option D: -9
If we raise -9 to an even power, it will be a positive number. Thus, -^66 could be -9.

To confirm our estimation, we can use a calculator or a math software to calculate -9^66. The result is approximately 3.8742049 × 10^62.

Therefore, the estimate for -^66 is option D: -9.