Option A
[tex](7 \times 10^{-3}) - (2.3 \times 10^{-6}) = 6.9977 \times 10^{-3}[/tex]
Solution:
Given expression is:
[tex](7 \times 10^{-3}) - (2.3 \times 10^{-6})[/tex]
To evaluate the expression, let us make the exponent of 10 same
[tex]2.3 \times 10^{-6} = 0.0023 \times 10^{-6+3} = 0.0023 \times 10^{-3}[/tex]
[ Here, decimal point is moved three times left, so add 3 ]
Therefore,
[tex](7 \times 10^{-3}) - (2.3 \times 10^{-6}) = (7 \times 10^{-3}) - (0.0023 \times 10^{-3})[/tex]
[tex]\text{Take the } 10^{-3} \text{ as common }[/tex]
[tex](7 \times 10^{-3}) - (0.0023 \times 10^{-3}) = 10^{-3}(7-0.0023)\\\\\text{ Solve for terms inside the bracket }\\\\(7 \times 10^{-3}) - (0.0023 \times 10^{-3}) = 10^{-3} \times 6.9977\\\\\text{Therefore, the simplified expression is: }\\\\(7 \times 10^{-3}) - (0.0023 \times 10^{-3}) = 6.9977 \times 10^{-3}[/tex]
Thus Option A is correct
