Answer:
D is correct
Step-by-step explanation:
Answer:
68/.75
Xy = 940
<span>and </span>
<span>Cost = 5(2x) + 5y + 10y (I chose y to be the side with brick). The cost equation simplifies to: </span>
<span>C = 10x + 15y </span>
<span>Replace y in the cost equation with 940/x: </span>
<span>C = 10x + 15(940/x) </span>
<span>C = 10x + 14100/x <---this is the equation you need to minimize. </span>
<span>C' = 10 - 14100/x^2 </span>
<span>10 - 14100/x^2 = 0 </span>
<span>14100/x^2 = 10 </span>
<span>x^2 = 14100/10 = 1410 </span>
<span>x = sqrt(1410) = 37.55 </span>
<span>y = 25.03 <---this is the length of the brick fence.</span>
