Question 430206
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Hi
C(x)= 2x^2-30x+570   Parabola opening upward
C(x)= 2[(x-7.5)^2 -56.25]+570   |Completing the square to find the Vertex
C(x)= 2(x-7.5)^2 -112.5 + 570 
C(x)= 2(x - 7.5)^2 + 457.50 
 Lowest cost is $457.50 or $458 to the nearest dollar
 (value OF C(7.5), the minimum point.