A school is selling sweaters to raise money. They sell 1200 sweaters when the price is $20. This year they wanna put the price up. A survey tells them that each time they raise they price by $2, they will lose 60 sales. What does the price have to be to get the maximum revenu?

Question

askme12345 · Answer

Okay 1200 * 20 = 24000
lose 60 sales = 1140 * 22 = 25,080
lose 60 more = 1080 * 24 = 25,920
lose 60 more = 1020 * 26 = 26,520
lose 60 more = 960 * 28 = 26,880
lose 60 more = 900 * 30 = 27,000 *GOES DOWN FROM HERE*
lose 60 more = 840 * 32 = 26,880
lose 60 more = 780 * 34 = 26520
you see that?

askme12345 · Answer

the answer is 900, because after that it starts going down?

anonymous · Answer

thank you so much, but were supposed to be able to solve it by f(x) = x^2 + x ... if you know what formula i mean

anonymous · Answer

i guess its called completing the square

askme12345 · Answer

this should help http://www.purplemath.com/modules/sqrquad.htm

anonymous · Answer

Youre supposed to be able to make two equations out of the question, and then substittute one of them into the other but I'm dumb and cant figure out what X is supposed to be.

askme12345 · Answer

one equation is price the other sweaters , im assuming?
So we have 1200-60x (since it decreases by 60, x amount of times) *we found out it was 5 times
and 2x+20 (since it increases by 2 dollars x times

anonymous · Answer

why is it +20?

askme12345 · Answer

20 is the original price of the sweater

anonymous · Answer

youve been a huge help, hopefully grade 11 math is easy enough for you :) thanks for your time

askme12345 · Answer

:)