Question

Solve the system of equations.

Answer 1

\[y = -0.04x ^{2} + 8.3x \]
y = 1.12x + 1.6

Answer 2

My choices:
A. no solution
B. (0.22, 1.85)
C. (179.28, 202.39)
D. (0.22, 1.85) and (179.28, 202.39)

Answer 3

well since they are both equal to y you can set the 2 equations equal to one another and then use the quadratic equation to solve for the solutions

Answer 4

How do I do that @captaincook

Answer 5

do you know the quadratic equation?

Answer 6

no

Answer 7

well then you could always plug the x values into the equations and see if the y values equal what the answer says it is.

Answer 8

Ah, I dont know how to...

Answer 9

how do i solve for x

Answer 10

ok one sec

Answer 11

−0.04x^2+8.3x = 1.12x + 1.6
Your goal is to create a quadratic equations which looks like this:
0 = a number x^2 +/- a number x +/- a number without x

Answer 12

one side needs to be zero

Answer 13

i recommend subtracting 1.12x from both sides. What does the equation look like after that?

Answer 14

7,1784 and 1.6 ?

Answer 15

−0.04x^2+7.18x =1.6

Answer 16

do you understand how I got there?

Answer 17

no exactly. im guessing the 7.18 was part of this 7.1784 and 0.04 for orignial equation. but why did you do that... idk why

Answer 18

−0.04x^2 + 8.3x = 1.12x + 1.6
-1.12x -1.12x
------------------------------------
−0.04x^2 +7.18x = 0 + 1.6
OR
−0.04x^2 +7.18x = + 1.6
OR
−0.04x^2 +7.18x = 1.6

Answer 19

Goal number one is to create an equation that looks like this: http://2.bp.blogspot.com/_YeNFpQ8GgCk/TMVFdA-C9FI/AAAAAAAACns/dqwZHrwBzL0/s400/Slide3a.jpg

Answer 20

in that picture,
a = -0.04
and x^2 follows it

b = 7.18
and a solitary x follows it

You still need to find c
c is your constant number, without a variable

Answer 21

to find c:
subtract 1.6 from both sides:
−0.04x^2 +7.18x = 1.6
- 1.6 = - 1.6
----------------------------------------
−0.04x^2 +7.18x - 1.6 = 0

now this your quadratic equation


in that picture,
a = -0.04
and x^2 follows it

b = 7.18
and a solitary x follows it

c = -1.6
(and no variable)

Answer 22

What about now? understand so far?

Answer 23

yes im kind of getting this for the most part... but if i had to do this by myself i wouldnt know how to start... thanks for doing all this work

Answer 24

SO goal 2 is to solve for x

Answer 25

there are about 5 ways to do this BUT luckily we don't have to...BECAUSE they give us solutions to test out. Just choose a number in your list and well try it out. pick one...

Answer 26

(there are also like 4 ways to do what we did first as well.....lol)

Answer 27

So this numbers you mean (179.28, 202.39)?
wow this is some confusing stuff

Answer 28

Oh trust....its crazy pellet for real...lol

Answer 29

what grade or class are you in?

Answer 30

its really funny that I wrote a cuss word and it wrote pellet hahahahah

Answer 31

but to answer your question...yes but only choose one number not both

Answer 32

12th grade
hahaha,, ya i was wondering why you wrote pellet

Answer 33

in order for (179.28, 202.39) to be the correct solution, that you must be able to plug 179.28 in for x in both equations and it =0 AND 202.39 into each equation and it equal 0

Answer 34

if one of them, plugged in does not equal 0...well than theres no need to try the other number because that option is wrong.

Answer 35

and its not yoru answer

Answer 36

x = 202.39

y=−0.04x2+8.3x
...lets start with the one that does NOT have a squared x...because if x = 202.39 and x is squared you must find the square root of x and that sucks.

y = 1.12x + 1.6
y = 1.12(202.39) + 1.6

Answer 37

y = 226.6768 +1.6

Answer 38

now remember y = 0

so,
0 = 226.6768 +1.6
o = 228.2768 is so false....lol so there for you dont need to plug it into teh other equation and you dont need to check the other number in your answer option....the option is NOT the right one

Answer 39

Wow! so what about 0.22

Answer 40

Wait a minute! if your equation is this: y = 1.12x + 1.6 than that means that 1.12 times anything plus anything has to equal 0 to be the correct answer....the only way that can happen is if x is negative or a 0. NONE of your solutions offer that.

Answer 41

try it with your calculator... i know u have one...lol

Answer 42

yes i have a calculator.

Answer 43

1.12 x 0.22 + 6 = 1.84

Answer 44

So the answer is no solution then

Answer 45

....i think so....my brain is fried...lol

Answer 46

its past midnight here

Answer 47

haha mine too! Thanks for all your help and explaining! I wush I could give ou more than a medal

Answer 48

hang on a sec

Answer 49

stuff that might help you in the class:

http://www.youtube.com/watch?v=KNwwu5wjcaA
http://www.youtube.com/watch?v=1T-rsltsWnM
-----> http://www.khanacademy.org/math/algebra/systems-of-eq-and-ineq

Answer 50

use khan academy for evvveeerrryyyyttthhhiinnggg, lol.....all classes and stuff

Answer 51

Thanks very much