The result of the operations expressed in scientific notation are :
A.)
[tex](1.54 \times {10}^{ - 2} ) + (2.86 \times {10}^{ - 1} )[/tex]
Converting each value to the same power of 10;
[tex](1.54 \times {10}^{ - 2} ) + (28.6 \times {10}^{ - 2} ) = (1.54 + 28.6) \times {10}^{ - 2} = 30.14 \times {10}^{ - 2} \: g[/tex]
B.)
[tex](7.023 \times {10}^{9} ) - (6.62 \times {10}^{7} )[/tex]
Converting each value to the same power of 10;
[tex](7.023 \times {10}^{9} ) - (6.62 \times {10}^{7} ) = (7.023 \times {10}^{9}) - (0.0662 \times {10}^{9}) = 6.9568 \times {10}^{9} \: g[/tex]
C.)
[tex](8.99 \times {10}^{ - 4} ) \times (3.57 \times {10}^{4} )[/tex]
From indices ; we add the powers when dealing with multiplication operation :
[tex](8.99 \times {10}^{ - 4} ) \times (3.57 \times {10}^{4}) = (8.99 \times 3.57) \times {10}^{( -4 + 4)} = 32.0943 \times {10}^{0} = 32.0943 = 3.20943 \times {10}^{1} \: {m}^{2} [/tex]
Therefore, the result of the expressions written in scientific notation are given above, except for the 4th which isn't well formatted.
Learn more :https://brainly.com/question/18360970