Question

can anyone help me with solving problems using quadratic functions?

Answer 1

..... same stuff eh :)

Answer 2

whatcha got....

Answer 3

The company discovered that it costs $45 to produce 2 calculators, $143 to produce 4 calculators, and $869 to produce 10 calculators. Using quadratic functions, find the cost of producing 7 calculators.

Answer 4

:) ill try this the elimination way this time and see what I get ;)

Answer 5

4a + 2b +c= 45 4a + 2b +c= 45
16a + 4b +c = 143 100a +10b +c = 869


(1/4) 4a + 2b +c= 45 4a + 2b +c= 45
16a + 4b +c = 143 100a +10b +c = 869

(-16) 1a + b/2 + c/4= 45/4 (-100) 1a + b/2 +c/4= 45/4
16a + 4b +c = 143 100a +10b +c = 869

-16a - 8b - 4c= -180 -100a - 50b -25c= -1125
16a + 4b + c = 143 100a + 10b + c = 869
---------------------- ---------------------
-4b -3c = -37 -40b -24c = -256

Answer 6

(-1/4) -4b - 3c = -37
-40b -24c = -256

(40) b + 3c/4 = 37/4
-40b -24c = -256

40b + 30c = 370
-40b -24c = -256
---------------------
6c = 114

c = 19

Answer 7

19 in the answer?

Answer 8

no, 19 is part of the quadratic equation ...like this:

ax^2 +bx +19 = y

Answer 9

-40b -24c = -256

-40b -24(19) = -256

-40b -456 = -256

-40b = -256 +456

-40b = 200

b = -5

ax^2 -5x + 19 = y so far ;)

Answer 10

4a + 2(-5) +19= 45

4a -10 +19 = 45

4a = 45 +10 -19

4a = 36

a = 36/4 = 9

y = 9x^2 -5x + 19; now what does this equal when x = 7?

Answer 11

y = 9(7)^2 -5(7) + 19

y = 9(49) -35 +19

y = $425 for 7 cameras

Answer 12

going over the math to se if I am right...

Answer 13

you were (:

a rock is launched from a cannon. after one second, the rock is 58 feet in the air; after 2 seconds the rock is 112 feet in the air. find the height, in feet, of the rock after 10 seconds in the air.

Answer 14

yay!!

Answer 15

so we have 2 points, 1,58 and 2,112, were missing a 3rd point.....but are we?

the third point is at time=0 the position of our rock is at a heaight of 0 so we have our 3rd point (0,0)

0a +0b +c = 0..... c = 0 that was easy enough for that one :)

1a +1b = 58
4a +2b = 112

a = 58-b so just substitute that back into the secnd one...

4(58-b) +2b = 112

232 -4b+2b = 112

-2b = 112 -232

b = -120/-2 = 60

b = 60
--------------------

a = 58-b

a = 58-60 = -2

y = -2x^2 +60x

y = -2(x^2 -30x) when x=10...

y = -2((10)^2 -30(10))

y = -2(100-300)

y = -2(-200)

y = 400 ...let me recheck my work ;)

Answer 16

it checks out...

Answer 17

correct! (:

Answer 18

i missed 3 questions on my trig test monday..... simple mistakes really, forgot to look at sign changes and even had right answers but wrong answer circled....

Answer 19

that's my problem usually too!

The company discovered that it costs $45 to produce 4 camera cases, $257 to produce 7 camera cases, and $792 to produce 12 camera cases. Using quadratic function, find the cost of producing 1 camera case.

Answer 20

i wonder if I can write a formula for this to make things easier on me :)

Answer 21

possibly. it doesn't give me one to use on any of these.

Answer 22

ill go to the other posting you did.... and try my matrix skills :)