## robandand 3 years ago 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?

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?

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

3. robandand

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

4. robandand

i guess its called completing the square

6. robandand

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.

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

8. robandand

why is it +20?

20 is the original price of the sweater

10. robandand

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