Explanation:
(3x10^4) + (7× 10²)
Simplify:
[tex]=3\times7\times10^4\times10^2[/tex][tex]\begin{gathered} =\text{ 21 }\times10^{4+2} \\ =\text{ 21 }\times10^6 \\ =\text{ 2.1 }\times10^1\times10^6\text{ = 2.1 }\times10^{6+1} \\ =2.1\times10^7 \end{gathered}[/tex]