a Let's start this with the formula for the area of a circle and r=x+3.25
cc
A &=& π r^2
&=& π (x+3.25)^2
Now that is one way to express the area of the largest disc. We can also expand that binomial using the Distributive Property for the second expression of the area.
b To find the area of the disc, we can use the area formula once we determine the radius for each disc. The smallest disc has a radius of x in. Since we are given that x=10.5, we can use that to find the area of the smallest disc.
The smallest disc can have an area of 110.25 π ≈ 346.185 in^2. The largest disc has an expression for it's radius of x+3.25 in. Let's substitute x=10.5 to get it's radius.
