Write: (8•10^-5)(5•10^-6) in scientific notation.

can someone ?

Yes; I can help.   The answer is:   4 * 10⁻¹⁰ .

Explanation:

  Given:  "Write:  "(8*10⁻⁵)(5*10⁻⁶)" in scientific notation.

   →  (8*10⁻⁵)(5*10⁻⁶) = 8 * 10⁻⁵ * 5 * 10⁻⁶
                                  = 8 * 5 * 10⁻⁵ * 10⁻⁶ 
                                  = 40 * 10⁽⁻⁵⁾⁺⁽⁻⁶⁾ ;

Note the following property of exponents:

             →   xᵃ * xᵇ  = x⁽ᵃ⁺ᵇ⁾ ;

                    So, we have:  

             →   40 * 10⁽⁻⁵⁾⁺⁽⁻⁶⁾  =  40* 10⁻¹¹ ;

                                          =  4 * 10⁻¹⁰ .