Answer:
[tex]2.8\times10^9[/tex]Explanation:
To evaluate the expression:
[tex]\mleft(7\times10^3\mright)\mleft(4\times10^5\mright)[/tex]First, we remove the bracket as shown below:
[tex]=7\times10^3\times4\times10^5[/tex]Next, we rearrange to bring the powers of 10 together:
[tex]\begin{gathered} =7\times4\times10^3\times10^5 \\ =28\times10^{3+5} \\ =28\times10^8 \\ =2.8\times10^9 \end{gathered}[/tex]