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Mathematics 7 Online
kaylak:

math help

kaylak:

@Vocaloid

Mehek:

Question?

Mehek:

The ones you selected for 1 are correct I'm not sure if option D is an answer too because \((x^2+x)^2\) = \(x^4+2x^3+x^2\) and the leading is a 4th degree

Mehek:

And for #2 it is option B)

kaylak:

https://s1.postimg.org/96teghhp5r/Capture.png number 4 a?

Mehek:

I am not sure about #3 you can ask vocaloid that

kaylak:

@Vocaloid

Vocaloid:

only look at the graph where x is between -2 and 3 what's the highest value the function obtains?

kaylak:

3?

kaylak:

is mehek correct on the other answers

Vocaloid:

make a tick mark where x = -2 make another tick mark where x = 3 between those two values, what's the highest y-value that the graph touches?

kaylak:

2

kaylak:

is the closest

Vocaloid:

good so 2 is your max I think Mehek is right for the other answers so far

Vocaloid:

kinda stumped on 4 tbh, let me think

kaylak:

i'm getting better at pre cal lol trying to solve some on my own

Vocaloid:

my pre-calc is kind of rusty, but I believe since there are 2 local maxima there are at least 2 "turns" which means a minimum degree of 3 [just considering those roots] then you would consider the complex roots (2+3i and 2 - 3i)

Vocaloid:

Mehek do you remember how do to this? ;_;

Mehek:

I haven't taken this :/ so nope

kaylak:

can y'all check these next few

kaylak:

am i correct and what is 5

Vocaloid:

sorry this is taking so long, but yes, your answers for 6 and 7 are right

Vocaloid:

anyway, for the intermediate value theorem, you would evaluate the function the left hand and right hand ends of the interval (for example, evaluate f(-5) and f(-4). now, treat f(-5) to f(-4) as a new interval, and if 0 is within that interval, then the original interval contains a 0

Vocaloid:

I think it's a little easier to explain with math than with English

kaylak:

-3,-2 one?

Vocaloid:

can you show me your work?

Vocaloid:

what did you get for f(-3) and f(-2)?

kaylak:

i'm graphing it honestly

Vocaloid:

you can also do it algebraically

kaylak:

-4,-3 appears to one too

Vocaloid:

Vocaloid:

(-3,-2) does not contain a 0 (-4,-3) does

kaylak:

-5,-4 -4,-3 1,2

kaylak:

i'm looking at the graph on mathway probably should try desmos

kaylak:

am i right so far?

Vocaloid:

you're missing [0,1] take a look at the graph I attached

Vocaloid:

other than that I think you're good

Vocaloid:

wolfram alpha is a very powerful mathematical software

kaylak:

i thought it was 0,1

Vocaloid:

I'm talking about the intervals not points

Vocaloid:

[0,1] means the interval x = 0 to x = 1 in between x = 0 and x = 1, there is one zero so [0,1] is an option

Vocaloid:

keep in mind the answer choices are intervals, not points

kaylak:

https://s1.postimg.org/9n9ibnzw9b/Capture.png but 0,1 is still an answer right and check 8 and help with 9?

Vocaloid:

8's good

Vocaloid:

for 9 I am not sure about formatting, but you would just find the possible roots using the p/q formula, and then test each root using synthetic division

Vocaloid:

(the rational root theorem, that is)

kaylak:

how would you do it if there isn't a q for example no x=3

Vocaloid:

hint: what is the coefficient on the highest powered term?

kaylak:

1

kaylak:

so x=1

Vocaloid:

x is not 1, but you would use that 1 to find the possible values of q

Vocaloid:

remember, q is all the possible factors of the coefficient on the highest powered term so what are the factors of 1?

kaylak:

+-2i and -1

Vocaloid:

just consider real numbers for now

Vocaloid:

the only factor of 1 is 1 so your possible values of q are +1 and -1 (or written as +- 1)

Vocaloid:

what about the constant? (4) what are the factors of 4?

kaylak:

2 and -2

Vocaloid:

keep going, you're missing 2 more

kaylak:

2i -2i

Vocaloid:

remember, we are only considering real roots for this (no i)

Vocaloid:

hint: 1 is a factor of every whole number, and if 1 is a factor of 4, what's also a factor of 4?

kaylak:

oh duh i'm going way ahead of myself

kaylak:

1,4

Vocaloid:

good so let's list out all the combinations

Vocaloid:

p = ± 4, ±2, ±1 q = ±1 so every possible combination of p/q can be tested as a root in synthetic division

Vocaloid:

so +4/-2, +1/1, etc.

kaylak:

so i need to divide 4/-2, 1/1 ?

Vocaloid:

yeah, you would divide all the possible combinations of p and q to find possible roots to test

kaylak:

so -2 and 1 ?

Vocaloid:

yes, those were two possible roots I used in the example you would need to divide ALL combinations of p and q to find ALL the roots, though. it's more than just those two

kaylak:

-1/1=-1

Vocaloid:

good keep going, there should be 6 possible roots

kaylak:

4/2=2

Vocaloid:

good

kaylak:

4/1=4 one more right?

Vocaloid:

good

kaylak:

2/1=2?

Vocaloid:

you already said this one ^^"

Vocaloid:

it's -4 to save you some time

kaylak:

oh oops

Vocaloid:

so our roots are +4, -4, +2, -2, +1, -1 so we can pick one root at a time to test -1 is a good choice, so perform synthetic division with x = -1 (or, x + 1 = 0)

kaylak:

ok lol

kaylak:

there shouldn't be a remainder right i get 10

Vocaloid:

that would be for +1 as a root not -1 ^^

Vocaloid:

for x = -1 the number that goes outside the synthetic division symbol is -1 I believe?

Vocaloid:

or is it 1

kaylak:

x=1 i just calculated

Vocaloid:

ah, so x = 1 is not a root try x = -1 as a root

Vocaloid:

awesome! so now we have x^2 +4 do you think x^2 + 4 = 0 has any more roots?

Vocaloid:

that is, does x^2 + 4 = 0 have any real number solutions? (no i)

kaylak:

we said -2

Vocaloid:

hint: does (-2)^2 + 4 = 0?

kaylak:

i just said that lol

Vocaloid:

again, does (-2)^2 + 4 equal 0?

kaylak:

yes

Vocaloid:

hint: (-2)^2 = (-2)*(-2) = ?

kaylak:

-4

Vocaloid:

try one more time

Vocaloid:

negative * negative = positive

kaylak:

4

Vocaloid:

good so (-2)^2+4 = 8, not 0 so -2 is not a root

kaylak:

oh crap duh i'm listening to an ll and doing pre cal

kaylak:

am done now

Vocaloid:

so do you think x^2 + 4 = 0 has any solutions?

Vocaloid:

good, it has no other solutions, so all possible roots have been found, making your problem complete

kaylak:

am almost done yay

kaylak:

10 should be right i need help with 11 mainly

Vocaloid:

I think you could do a piecewise function that excludes x = -2

Vocaloid:

and put (x-3) in the denominator to make that vertical asymptote

kaylak:

so for example i could say 6x^3-2x^2-x-3 for denominator?

Vocaloid:

I guess but you don't need to make it that complex

Vocaloid:

if you just put 1/(x-3) as your function it'll work fine

Vocaloid:

(it's your choice though)

Vocaloid:

anyway, after you have your function, you can write it in piecewise notation { f(x) = ______ from (-infinity,-2) { f(x) = _______ (same function) from (-2,infinity)

kaylak:

oh ok

kaylak:

so pick a function? for the numerator

Vocaloid:

actually come to think of it there's a better way

Vocaloid:

if you put (x+2) in your numerator AND the denominator this should give you a hole at x = -2

kaylak:

so x+2/x+2-x/3?

Vocaloid:

almost

Vocaloid:

(x+2)


(x+2)(x-3) the
is a fraction bar

Vocaloid:

whoops

Vocaloid:

(x+2) fraction bar (x+2)(x-3) should do it

kaylak:

how would i explain how i determined it

Vocaloid:

using the steps I have outlined above

Vocaloid:

\(\color{#0cbb34}{\text{Originally Posted by}}\) @Vocaloid if you put (x+2) in your numerator AND the denominator this should give you a hole at x = -2 \(\color{#0cbb34}{\text{End of Quote}}\)

Vocaloid:

\(\color{#0cbb34}{\text{Originally Posted by}}\) @Vocaloid and put (x-3) in the denominator to make that vertical asymptote \(\color{#0cbb34}{\text{End of Quote}}\)

kaylak:

is 10 right? and 12? i'm about to solve 12

Vocaloid:

yeah I think 10's good

kaylak:

12 is a

kaylak:

1 more after this to check

Vocaloid:

12 is good

kaylak:

13?

Vocaloid:

yes good

Vocaloid:

for 14 find the least common denominator convert both fractions to have the LCD then just add

kaylak:

14 i have to solve

Vocaloid:

hint: to start, try factoring both denominators then the LCD will be a bit more obvious

kaylak:

x x -2 x

Vocaloid:

uh I'm not sure what this means ^^

kaylak:

x x -4 1

Vocaloid:

try using parentheses to be more clear

kaylak:

x^2=(x*x) right

kaylak:

-2x=(-2*x)

Vocaloid:

if you have terms being added and subtracted you cannot factor each term individually, you have to consider the expression as a whole

Vocaloid:

for example, for (x^2-2x) what happens if you factor out x? make sure to keep parentheses in your answer

kaylak:

ypu have (x-2)

kaylak:

?

Vocaloid:

good, so we get (x)(x-2) as the new denominator now try factoring (x^2-4) using difference of squares

kaylak:

x+2 x-2

Vocaloid:

good so let's compare the left denominator and the right denominator left: (x)(x-2) right: (x+2)(x-2) how can we get them both to be the same thing?

kaylak:

x^+2 x-2?

Vocaloid:

uh I'm not sure what you mean by that

kaylak:

x*x=x^2

Vocaloid:

I think you're a little off track ^^ let me help out

Vocaloid:

left: (x)(x-2) right: (x+2)(x-2) if we multiply the "right" by x and the "left" by (x+2) what do we get?

Vocaloid:

*** note: do not distribute any parentheses yet

kaylak:

x^4-2x^3-4x^2+8x

Vocaloid:

please do not distribute any parentheses yet

Vocaloid:

you should have gotten: left: (x)(x-2)(x+2) right: (x+2)(x-2)(x) right?

kaylak:

oh ok so you wanted it exactly literally ok i'm over here trying to combine it

Vocaloid:

yeah, sorry if I wasn't clear ^_^"

kaylak:

piecewise function are not until next unit lol just looked for that other question it's ok

Vocaloid:

anyway, remember that, in order to keep the value of a fraction the same, you would multiply the numerator AND the denominator by the same value

Vocaloid:

so for the left-fraction, multiply the numerator and the denominator by (x+2) and then for the right fraction, multiply the numerator and the denominator by x

Vocaloid:

if you do your math correctly you should have two fractions with the same denominator then you can just add the numerators and put that over the new denominator if that makes sense

Vocaloid:

like: (A/C) + (B/C) = (A+B)/C

kaylak:

so multiply with the x(x-2)(x+2) we have?

Vocaloid:

let me rephrase this ^^

kaylak:

or by the orginal equation

Vocaloid:

your original problem is (x-4)/(x^2-2x) + (4/(x^2 - 4)) apply the multiplications to this ^

Vocaloid:

(you can use the factored form if that's easier)

kaylak:

x-4*(x+2)=-3x+2 x^2-2x*x+2=-x^2+2 4*x=4x x^2-4*x=x^2-4x

Vocaloid:

check your math again

Vocaloid:

your denominators should be equal

Vocaloid:

use the factored form if that's simpler

Vocaloid:

(x-4)/ [x(x-2)] + (4/[x+2][x-2]) ^ apply the multiplications to this

Vocaloid:

you should get x(x-2)(x+2) as your denominator

kaylak:

x+2/x^2+2? answer

kaylak:

mathway says the numerator is x+4?

Vocaloid:

try leaving things in factored form instead of expanding things out

Vocaloid:

at the very end, you can do the expansions

Vocaloid:

I wouldn't trust mathway, their software isn't good for calculations

Vocaloid:

also can we open a new question? this one is lagging a lot

Vocaloid:

I can transfer my work over

kaylak:

so x+2 for numerator is correct and sure

Vocaloid:

I don't think x + 2 is the correct numerator

kaylak:

im confused

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