Estimation :
20/0.05 = 400
<span>A(t) = −(t − 8)2 + 535
You would like to find the maximum of this function:</span> −(t − 8)^2<span>This part is always negative or zero as a number squared cannot be negative and you multiply by -1: Thus the maximum of this part MAX:</span>−(t − 8)^2=0
<span>The max will be when t=8 and its value is 535
</span>
Let x be the number of CDs we buy and y the number of CDs we sell.
Each CD sell for $1.5, then the total of money we earn is $1.5y.
Each CD bought for $5, then the total money spent is $-5x
Add the above values like this:
1.5y-5x
We have $20, add them like this:
1.5y-5x+20
Since we want to have<span> at least $10 left when you leave the store, then
we deduce the equation:
</span>
Answer: C
The graph is continuous because there can be fractional values for time
Anything times 0 is 0 so the answer is 0