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Mathematics 7 Online
OpenStudy (anonymous):

can anyone help??

OpenStudy (anonymous):

OpenStudy (anonymous):

OpenStudy (anonymous):

i think i just neeed to do the last 4 steps its asking at the bottom

OpenStudy (anonymous):

can anyone help or understand how to do that?

OpenStudy (xapproachesinfinity):

what you think u should be?

OpenStudy (xapproachesinfinity):

any ideas?

OpenStudy (xapproachesinfinity):

oh there two pages last 4 you are reffering to page 2 right?

OpenStudy (anonymous):

its all one problem

OpenStudy (xapproachesinfinity):

okay! first pages looks like an example to me

OpenStudy (anonymous):

i think i need to answer the 4 questions at the bottom of pg 2

OpenStudy (xapproachesinfinity):

anyways we are doing this \(\sqrt{(x^2-x)+7}=2(x^2-x)-1\) 1) is about the u

OpenStudy (xapproachesinfinity):

any idea?

OpenStudy (anonymous):

there is no u there, but in pg 11 it says let u= t^2-3t is that right?

OpenStudy (xapproachesinfinity):

it say what would u represent i may reading this incorrectly lol

OpenStudy (xapproachesinfinity):

they want you to suggest a u for that equation

OpenStudy (anonymous):

idk im very confused i dont see a U?? :S

OpenStudy (xapproachesinfinity):

no there is no u in the problem! what they are telling you is do substitution instead of solving for x we solve for a new variable u but we need first to make some kind of substitution if you looked at the first page you have they give you an example

OpenStudy (xapproachesinfinity):

i think you didn;t read what that page is saying otherwise you would be confused what u is lol

OpenStudy (xapproachesinfinity):

because that first page explains it all!

OpenStudy (anonymous):

i did read it.

OpenStudy (xapproachesinfinity):

lol! okay no problem so we need to do substitution to some variable u I'm speaking of this equation now \(\sqrt{(x^2-x)+7}=2(x^2-x)-1\)

OpenStudy (xapproachesinfinity):

this equation looks a mess for now that's why we do u to have only one good looking variable

OpenStudy (anonymous):

so we need to replace (x^2-x) with u right

OpenStudy (xapproachesinfinity):

so we can solve easily ah yes you are catching good going so far

OpenStudy (xapproachesinfinity):

\(\sqrt{u+7}=2u-1\) letting u=x^2-x yes

OpenStudy (xapproachesinfinity):

now we can solve for u before we go back to x

OpenStudy (xapproachesinfinity):

following?

OpenStudy (anonymous):

yea

OpenStudy (xapproachesinfinity):

\(\sqrt{u+7}=2u-1 \Longrightarrow u+7=(2u-1)^2\)

OpenStudy (xapproachesinfinity):

agree with this step or no?

OpenStudy (xapproachesinfinity):

i took square of both sides

OpenStudy (anonymous):

to get rid of the sqrt, yea

OpenStudy (xapproachesinfinity):

good! so now \(u+7=4u^2-4u+1 \Longrightarrow 4u^2-5u-6=0\)

OpenStudy (xapproachesinfinity):

we got a quadratic!

OpenStudy (xapproachesinfinity):

can we factor that!

OpenStudy (anonymous):

wait

OpenStudy (xapproachesinfinity):

yes! any questions

OpenStudy (anonymous):

to get 4u^2 -5u-6, you just did -u-7 from both sides right?

OpenStudy (xapproachesinfinity):

yes!

OpenStudy (anonymous):

and then we need to factr that to (4u+3)(u-2)?

OpenStudy (xapproachesinfinity):

now we factor to \((u-2)(4u+3)=0\)

OpenStudy (xapproachesinfinity):

yes excellent

OpenStudy (anonymous):

and use zpp?

OpenStudy (xapproachesinfinity):

solve for u what is zpp lol never heard this haha

OpenStudy (anonymous):

zero product property lol

OpenStudy (xapproachesinfinity):

i guess you mean u-2=0 or 4u+3=0 u=2 or u=-3/4

OpenStudy (anonymous):

yep

OpenStudy (xapproachesinfinity):

eh i see i never named anyhing it just makes sense to me with no name haha

OpenStudy (xapproachesinfinity):

now we solved for u but we still not finished for x

OpenStudy (xapproachesinfinity):

remember that we let u=x^2-x right

OpenStudy (anonymous):

so for the first question its u= *3/4 and u=2 right

OpenStudy (xapproachesinfinity):

so we have \(x^2-x=2 ~~or~~ x^2-x=-3/4\)

OpenStudy (xapproachesinfinity):

oh no first question to just answer u=x^2-x that is it

OpenStudy (xapproachesinfinity):

we are actually doing all those 4 question in one go

OpenStudy (anonymous):

ohh okay

OpenStudy (xapproachesinfinity):

once we finish you put it in order 1 put what we did 2 put what we did

OpenStudy (xapproachesinfinity):

here i went to answer those as one question lol they supposed to be one it is just that they want you to understand it part by part

OpenStudy (anonymous):

okay

OpenStudy (xapproachesinfinity):

2 we did we wrote the equATION WITH ONLY U

OpenStudy (anonymous):

gotcha

OpenStudy (xapproachesinfinity):

3 we did we solved for u u=2 u=-3/4

OpenStudy (xapproachesinfinity):

we are in 4 now :)

OpenStudy (xapproachesinfinity):

\(x^2-x=2 ~~or x^2-x=-3/4 \) we solve this now

OpenStudy (xapproachesinfinity):

two quadratic equations

OpenStudy (xapproachesinfinity):

\(x^2-x-2=0 ~~~or ~~~ 4x^2-4x+3=0\)

OpenStudy (xapproachesinfinity):

looks good to you?

OpenStudy (anonymous):

no lol

OpenStudy (xapproachesinfinity):

may be i wen too fast haha x^2-x=2 x^2-x-2=0 after subtracting 2 from both ssides

OpenStudy (anonymous):

how did you get 4x^2-4x+3

OpenStudy (xapproachesinfinity):

the other one x^2-x=-3/4 ===> 4(x^2-x)=-3 (multiplied 4 both sides) 4x^2-4x=-3 4x^2-4x+3=0 added 3 to both sides

OpenStudy (xapproachesinfinity):

clear now i guess haha

OpenStudy (xapproachesinfinity):

i just wanted to have a nice format i dislike fractions haha

OpenStudy (xapproachesinfinity):

good or nor good?

OpenStudy (anonymous):

i was just trying to understand it sorry, im a slow learner lol i got it tho

OpenStudy (anonymous):

i got it

OpenStudy (xapproachesinfinity):

hmm you are good learner as i see it :)

OpenStudy (anonymous):

aw thanks aha :))

OpenStudy (xapproachesinfinity):

we solve \(x^2-x-2=0 \Longrightarrow (x+1)(x-2)=0\)

OpenStudy (xapproachesinfinity):

this one 4x^2-4x+3=0 does not have real solutions

OpenStudy (xapproachesinfinity):

so we just solve (x+1)(x-2)=0

OpenStudy (xapproachesinfinity):

zpp lol

OpenStudy (anonymous):

x=1 and 2

OpenStudy (anonymous):

-1,+2

OpenStudy (xapproachesinfinity):

yes great job

OpenStudy (xapproachesinfinity):

that for step 4 and we are good!

OpenStudy (anonymous):

cool thanks so much

OpenStudy (xapproachesinfinity):

no problem

OpenStudy (anonymous):

you are a great teacher aha

OpenStudy (xapproachesinfinity):

not really :) i suck at some stuff haha

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