Question

Multiply (1.2 ⋅ 1028) ⋅ (3 ⋅ 10−19). Express the answer in scientific notation.

a) 3.6 ⋅ 109
b) 3.6 ⋅ 1010
c) 36 ⋅ 109
d) 36 ⋅ 1010

Answer 1

The answer would be A. 3.6 × 10^9

Answer 2

Answer: a)
`3.6\cdot10^9`

Explanation:

The given multiplication problem is

`(1.2\cdot10^(28))(3\cdot10^(-19))`

First we open the parenthesis, and then multiply corresponding terms.

`1.2\cdot10^(28)\cdot3\cdot10^(-19)\\=(1.2\cdot3)\cdot(10^(28)\cdot10^(-19))\\=3.6\cdot10^(28+(-19)).....[\text{by using law of exponents }a^ma^n=a^(m+n)]\\=3.6\cdot10^(28-19)\\=3.6\cdot10^9`

Thus, a) is the right answer.