Question

Select all the expression that equal 4 X 106 O 406 O 400,000 (2 x 10) (2 x 10-2) O 40 x 105

Answer 1

To check which options are correct, we can write out all the options in standard form.

OPTION 1:

`40^6=4096*10^6`

This option is NOT correct.

OPTION 2:

`(1.2*10^9)/(3*10^2)`

Applying the laws of indices, we have

`\begin{gathered} (1.2)/(3)*10^(9-2) \\ =0.4*10^7 \\ =0.4*10*10^6^{} \\ =4*10^6 \end{gathered}`

This option is CORRECT.

OPTION 3:

`400000=4*10^5`

This option is NOT correct.

OPTION 4:

`(2*10^8)(2*10^(-2))`

Applying the laws of indices, we have

`\begin{gathered} 2*2*10^(8+(-2)) \\ =4*10^6 \end{gathered}`

This option is CORRECT.

OPTION 5:

`\begin{gathered} 40*10^5 \\ =4*10*10^5 \\ =4*10^6 \end{gathered}`

This option is CORRECT.