ANSWER
The solution is
EXPLANATION
We want to solve the simultaneous equations
and
.
We substitute equation (2) in to equation (1), to obtain
This has now become a linear equation in a single variable .
We solve for x by grouping like terms.
We divide through by negative 3 to get;
.
Hence, the solution is
Answer:
The area is growing at a rate of
Step-by-step explanation:
<em>Notice that this problem requires the use of implicit differentiation in related rates (some some calculus concepts to be understood), and not all middle school students cover such.</em>
We identify that the info given on the increasing rate of the circle's radius is 3 and we identify such as the following differential rate:
Our unknown is the rate at which the area (A) of the circle is growing under these circumstances,that is, we need to find .
So we look into a formula for the area (A) of a circle in terms of its radius (r), so as to have a way of connecting both quantities (A and r):
We now apply the derivative operator with respect to time () to this equation, and use chain rule as we find the quadratic form of the radius:
Now we replace the known values of the rate at which the radius is growing ( ), and also the value of the radius (r = 12 cm) at which we need to find he specific rate of change for the area :
which we can round to one decimal place as: