Answer:
D
Step-by-step explanation:
The area and the radius of a sphere are related by the formula:
A=4πr^2
Let’s say this is A1 and r1
Now the radius is tripled. This means r2 = 3r1
The new area thus becomes: A = 4 * (3r)^2 * π = 36πr^2
Comparing A1 and A2 , we can see that A2 = 9A1
Example:
This suggests two solutions,
and
.
However, upon plugging these solutions back into the equation, you get
which checks out, but
does not because
is defined only for
(assuming you're looking for real solutions only). So, we call
an extraneous solution, and the complete solution set (over the real numbers) is
.
I’m pretty sure this is correct.
Answer:
The 99th tower contains 9900 blocks.
Step-by-step explanation:
From the question given, we were told that the nth tower is formed by stacking n blocks on top of an n times n square of blocks. This implies that the number of blocks in n tower will be:
n + n²
Now let us use the diagram to validate the idea.
Tower 1:
n = 1
Number of blocks = 1 + 1² = 2
Tower 2:
Number of blocks = 2 + 2² = 6
Tower 3:
Number of blocks = 3 + 3² = 12
Using same idea, we can obtain the number of blocks in the 99th tower as follow:
Tower 99:
n = 99
Number of blocks = 99 + 99² = 9900
Therefore, the 99th tower contains 9900 blocks.
