9. Write the expression using scientific notation.
(2.5 * 10 ^ 4)(4 * 10 ^ 3)
A.10 * 10 ^ 7
B.10 * 10 ^ 8
C.1 * 10 ^ 8
D.10 * 10 ^ 12
C. 1 * 10 ^ 8
To write the expression using scientific notation, we can multiply the two numbers together and then express the result as a number between 1 and 10 multiplied by a power of 10.
(2.5 * 10 ^ 4)(4 * 10 ^ 3) = (2.5 * 4) * (10 ^ 4 * 10 ^ 3)
= 10 * 10 ^ (4 + 3)
= 10 * 10 ^ 7
So, the correct option is A. 10 * 10 ^ 7.
To write the expression using scientific notation, we need to simplify the multiplication and express the result in the standard form a × 10^n, where a is a number between 1 and 10, and n is an integer.
Step 1: Simplify the multiplication.
(2.5 * 10^4)(4 * 10^3) = 2.5 * 4 * 10^(4+3) = 10 * 10^7
Step 2: Write the result in scientific notation.
Since 10 * 10^7 can be expressed as 10^1 * 10^7, we add the exponents and write it as 10^(1+7) = 10^8.
Therefore, the expression (2.5 * 10^4)(4 * 10^3) written in scientific notation is C. 1 * 10^8.