Answer:
a is the correct option.
Step-by-step explanation:
We have been given the population model is 
Here x represents number of weeks and f(x) is population of frog after x weeks.
For x= 6, we have

It means that the population after 6 weeks is 960.
Hence, f(6)=960 represents the population after 6 weeks.
a is the correct option.
Answer:
and 
Step-by-step explanation:

Discriminant

If the discriminant is a negative number then the roots of the equation are imaginary

So, the two solutions are
and 
The working out would be-
Pi x radiussquared
Pi x 64 = 201.0619298297468
Rounded to 2 decimal places =
201.06 feet2
Answer:

Step-by-step explanation:
Given
AB = 48, AC = 64, and BC = 80
Required
Determine the ratio of cosB
The first step is to determine, which type of triangle it is.
Checking for Right Angled Triangle
For a triangle to be a right angled triangle, the square of the largest side must be equal to the sum of squares of other sides
This implies that:



<em>Hence, the triangle is a right angled triangle [See attachment]</em>
From trigonometry;

The adjacent of B = 48 while the hypotenuse is 80;
Hence;

Hence, the ratio of cos B is 
<span>8x^2 -50
= 2(4</span><span>x^2 - 25)
= 2(2x + 5)(2x - 5)
hope it helps </span>