A computer analysis shows that the cost C for a company to make x units of a certain product is give

题目

A computer analysis shows that the cost C for a company to make x units of a certain product is given by company to make x units of a certian product is given by C=0.1x^2 + 0.8x+7.how many units can be made for $50?

答案

By the question,it's easy seen that C=50,therefore we have the equation below
50=0.1x^2+0.8x+7
500=x^2+8x+70
x^2+8x-430=0
(X+4)^2=446
x=±√446-4
Cause x>0,hence that x=√446-4=17.12