The cost to produce a product is modeled by the function f(x) = 5x^2 − 70x + 258 where x is the number of products produced. Complete the square to determine the minimum cost of producing this product.

5(x − 7)^2 + 13; The minimum cost to produce the product is $13.
5(x − 7)^2 + 13; The minimum cost to produce the product is $7.
5(x − 7)^2 + 258; The minimum cost to produce the product is $7.
5(x − 7)^2 + 258; The minimum cost to produce the product is $258.

i thiink its b

2 answers

f(x) = 5x^2 − 70x + 258
= 5(x^2 - 14x + 49-49) + 258
= 5(x-7)^2 - 245 + 258
= 5(x-7)^2 + 13
my choice is a)

The minimum cost is 13, obtained when x = 7
5(x − 7)2 + 13; The minimum cost to produce the product is $13.