Answer: a) [tex]3.6\cdot10^9[/tex]
Step-by-step explanation:
The given multiplication problem is
[tex](1.2\cdot10^{28})(3\cdot10^{-19})[/tex]
First we open the parenthesis, and then multiply corresponding terms.
[tex]1.2\cdot10^{28}\cdot3\cdot10^{-19}\\=(1.2\cdot3)\cdot(10^{28}\cdot10^{-19})\\=3.6\cdot10^{28+(-19)}.....[\text{by using law of exponents }a^ma^n=a^{m+n}]\\=3.6\cdot10^{28-19}\\=3.6\cdot10^9[/tex]
Thus, a) is the right answer.
