Answer:
c. 
Step-by-step explanation:
We have been given that the area in square units of an expanding circle is increasing twice as fast as its radius in linear units
We will use derivatives to solve our given problem.
We know that area (A) of a circle is equal to
.
Let us find derivative of area function with respect to time.

Bring out constant:

Using power rule and chain rule, we will get:

Here
represents change is radius with respect to time.
We have been given that area of an expanding circle is increasing twice as fast as its radius in linear units. We can represent this information in an equation as:





Therefore, the radius is
and option 'c' is the correct choice.
Answer:
The equation of the straight line in point-slope form

The equation of the straight line
7x -9y +36 =0
Step-by-step explanation:
<u><em>Step(i):-</em></u>
Given that the points (0,4) and (-9,-3)
The slope of the line

<u><em>Step(ii):-</em></u>
Equation of the straight line passing through the point (0,4) and having slope m = 7/9


9 y - 36 = 7x
9y = 7x + 36

Slope - intercept form

<u><em>Final answer:-</em></u>
The equation of the straight line in point-slope form

The equation of the straight line
7x -9y +36 =0
Because it has already been factored, we can solve it straight away. Now, since m is a variable, we yield the same result if m = 0 or m = 3 because we have two components to this equation.
We can either have m = 0 or m - 3 = 0
Hence, m is either 0 or 3
Answer:
Step-by-step explanation:
There are only 5 solutions:
x=-1
x=-1/3
x=0
x=1
x=8/3
See the graph
In blue: y=[x]²
In red : y=x+2(x-[x])