Question

Select the expression that is equivalent to 3x105+5x108.

15x1013



300,000+500,000,000



15x10-40



300,000x500,000,000

Answer 1

When you're dealing with scientific notation (especially when you use an order of operations such as adding on it), it's important to know that you cannot add 10^2 to 3 (for example).

(3 x 10^5) + (5 x 10^8)

When adding exponents, you're only adding the exponents together and not changing the original number (10).

5 + 8 = 13

We now have a sum of 3x5 x10^13

Multiply 3 by 5 to get your new expression.

3 x 5 = 15

15 x 10^13 is what we're left with.

Your answer is A.)

I hope this helps!