Question

Max-Min problem please help

Answer 1

Two hongkongers coming to help you xD *laughcry*

Answer 2

@Callisto and I come from Hong Kong :)

Answer 3

yay xD

Answer 4

\[C=\left\{\begin{array}{lr}50x&\mbox{if }x\le10\\(50-0.5(x-10))x=(55-0.5x)x&\mbox{if }x>10\end{array}\right.\]

Answer 5

do we find the first derivative of this???

Answer 6

55-x

Answer 7

This function is discontinuous and non-differentiatable, are you telling me to differentiate it xD

Answer 8

i need to find the x and what is the maximum total group charge to the company

Answer 9

what's the maximum of (55-0.5x)x... hmm...

Answer 10

yep, sorry, differentiation will work. Solve for c'(x)=0 :)

Answer 11

sorry i dont understand this still its really hard for me because i m not in calculus

Answer 12

Do you know completing square?

Answer 13

Do you know how to find the vertex a quadratic graph?

Answer 14

yes

Answer 15

Just from a given quadratic equation?

Answer 16

yes

Answer 17

Then, what is the vertex of (55-0.5x)x = 0?

Answer 18

(55,1512.5)

Answer 19

Right. Since the graph opens downwards, the y-coordinate gives you the maximum value of the function.

Answer 20

ok the x=55 and the maximum total group charge to the company is 1512.5

Answer 21

I guess that's it.

Answer 22

ok thank you :)

Answer 23

Thanks @kc_kennylau