Question

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

Answer 1

Put the numbers into \[y =ax ^{2}+bx+c\] form. So your points would be (2, 450) (4, 143) and (10, 869). Plug the x in for the x in the equation and y in for y in the equation and then enter it into your matrix (3x4) in the graphing calculator, and it will give you 3 numbers. Put those in for a b and c and you have your equation to find the y for 7

Answer 2

i don't have a graphing calculator. that's why i posted the question so someone could help.

Answer 3

ok, do you know how to do augmented matrices?

Answer 4

i don't know how to do it at all. i have 5 questions on the assignment. and don't know how to do it. the online tutuorial doesn't explain how to do it very well or enough for me to figure it out.

Answer 5

Alright. Do you know what they are?

Answer 6

know what ?

Answer 7

What an augented matrice is?

Answer 8

no

Answer 9

It is a table kind of that gives you the a,b, c of the quadratic equation. You have to get it to be
101a
010b
101c

Answer 10

Your matrix would look like
4 2 1 450
16 4 1 143
100 10 1 869

Answer 11

Now you have to solve and such to transform you r matrix into the one above

Answer 12

you have to get the ones in the order of 2,1 3,1 3,2 2,3 1,3 1,2

Answer 13

then what?

Answer 14

correction of the order up above, it should be
1 0 0 A
0 1 0 B
0 0 1 C

Answer 15

to get the zeros, you have to do stuff like Row 1 x -25 ( multiply each number in row 1 by -25) and then row 1 + row 3=Row 3 so the first number in row 3 cancels out to 0. and then you can divide row 1 by -25 to get the original row again. But make sure when you add rows you add all of the numbers to the corresponding numbers.

Answer 16

You keep doing this to each place where you need a zero but make sure you don't lose any zeros making new zeros otherwise you'll get a continuous loop of math

Answer 17

then?

Answer 18

you do this to get all the zeros. so next you would do row 1 x -5 and then add it to row 3 to cancel out the 10 and make it 0

Answer 19

there's no easier way to find the answer?

Answer 20

only if you have a graphind calculator

Answer 21

now try solving for the third zero

Answer 22

Unless I'm missing something, can't the initial equations:

45 = (2^2)a+2b+c
143 = (4^2)a + 4b + c
869 = (10^2)a + 10b + c

...be solved in about 5 lines with normal Gaussian elimination? I may, of course, have misunderstood the set-up of this, so feel free to correct me.

Answer 23

I have never heard of gaussian before

Answer 24

you should gett the second zero by multiplying r1 x -4 and then adding it to r2.

Answer 25

'Gaussian elimination' is just a fancy way of saying use two equations to eliminate c, then the others to eliminate a or b, and then you have one. put that back in... Matrices are good in theory but almost always terribly laborious in practice if it's not a computer doing it.

To start:
45 = (2^2)a+2b+c (*)
143 = (4^2)a + 4b + c (**)
869 = (10^2)a + 10b + c (***)

(**) - (*) => 98 = 12 a + 2b
(***) - (**) => 726 = 84a + 6b

Repeat for these two and you have it done.

Answer 26

would you be willing to help me with the 5 questions?

Answer 27

Are they all a similar thing? Because if so seeing one should help you to do the others, but I could offer you more advice if you need it I guess. As there are 4 more I may just finish this one off for you:

Carrying on:
98 = 12 a + 2b (1)
726 = 84a + 6b (2)

(2) = 3 x (1)

=> 432 = 48 a => a = 9.

It follows that b = ... and c = ....

Answer 28

well it's not so much of advice, i have no idea how to do it.

Answer 29

OK post one more and I'll see what I can do to help. But I'm going to assume whatever you have to do, matrices is not it.

Answer 30

i can't. it only shows one question at a time

Answer 31

OK - do you need to give the answer to get the next one?
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Well if you solve the equations as above, you should find a = 9, b = -5 c = 19

So the quadratic is "Cost = 9x^2 - 5x + 19", where x is the number of calculators. See if you can work out the cost of 7.

Answer 32

425?

Answer 33

I believe so.

Answer 34

that was correct. so do you think you could help with the others

Answer 35

Yes I probably can help for a bit if you post the next one, but I will try a little more this time to help you get the answer instead of giving it, so then you should be able to do the rest.

Answer 36

After a second, the rock is 58 feet in the air; after two seconds , it is 112 feet in the air. find the height, in feet, of the rock after 10 seconds.

Answer 37

Does it say you have to use a quadratic like before, or is this linear or something? It effects how you go about it.

Answer 38

quadratic. they all are.