Answer:
The first one
Step-by-step explanation:
3 to the negative second power is written like this:

.
When simplifying an expression with a negative exponent, you take a positive version of the exponent, in this case that would be 2, and apply that to the base.
After doing that, we have 9.
The next step is to put one over that number.
In this case, now after doing that the answer is

.
Hope this helps!
Answer:

Step-by-step explanation:
In order to add or subtract numbers in scientific notation, the powers of ten must have the same exponent. In this caes the diameter of an average human body cell is a power of -4 and the diameter of a plant cell is a power of -3. In order to add them, we can move the decimal over for the body cell diameter:

Add the two values: 
⇒ common ratio =r=3 and the given sequence is geometric sequence. Where an is the nth term, a is the first term and n is the number of terms. ⇒ 12th term is 708588 .
(May be wrong for some other users, although it's correct for me.)
Answer:
A circle is a bounded object with points from its center to its circumference is equidistant.
Area of a circle = πr²
Where :
π = pi = 3.14
R = radius = diameter / 2 = 20m / 2 = 10m
3.14 x 10² = 314m²
Number of boxes needed to cover the garden = area of the garden / coverage of one box
314m² / 58m² = 5.14
5 boxes to one significant figure
<h2>
Brainliest pls</h2>