Which of the following expressions is written in scientific notation?
a. 73.4 x 10^5
b. 0.09 × 10^7
c. 80 x 10^3
d. 4.22 x 10^–3***
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To determine which of the given expressions is in scientific notation, we need to understand what scientific notation is and how it is written.
Scientific notation is a way to express numbers that are very large or very small by using powers of 10. It is written in the form of "a x 10^b", where "a" is a number between 1 and 10 (excluding 10), and "b" is an integer.
Let's evaluate each expression to see which one is in scientific notation:
a. 73.4 x 10^5:
The number 73.4 is larger than 10, so it is not in scientific notation.
b. 0.09 × 10^7:
The number 0.09 is less than 1, so it is not in scientific notation.
c. 80 x 10^3:
The number 80 is larger than 10 and does not have a decimal point, so it is not in scientific notation.
d. 4.22 x 10^–3:
The number 4.22 is between 1 and 10, and it is multiplied by 10 raised to a negative exponent (-3). This expression is written in scientific notation.
Therefore, the correct answer is option d.