Can someone please explain and show me how to do these please. 1.) x^2 – 8x + 15
2.) a^2 – a – 20
3.)a^2 – 5a – 20
4.)a^2 + 12ab + 27b^2
5.)2a^2 + 30a + 100

- anonymous

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- anonymous

@Roya Could you help me?

- anonymous

Anyone?

- anonymous

all of 'em?

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## More answers

- anonymous

dear i 'll . u need to find out x and a ?

- anonymous

Yes please. Well, yeah. :/
It's factoring trinomials.

- anonymous

Instructions say --> Factor each trinomial below. Please show your work

- anonymous

x^2-8x+15=0
(x-3)(x-5)

- anonymous

for ex for this one think about two numbers which their multiple product be 15 and their product of sum be -8

- anonymous

we know that 3*5 is 15
and we check if the some of them is -8 or not ?
5+3=8
but with a little experience we guess -3+-5=-8

- anonymous

I see.

- anonymous

20=10*2
10*2=8
10-2=8
20=5*4
5+4=9
5-4=1
4-5=-1
so can u find out the factors ?

- anonymous

10 and 5

- anonymous

u mean (a-10)(a-5) ?

- anonymous

Wait, which one are we on?

- anonymous

The second one?

- anonymous

second

- anonymous

I'd say the factors would be -10 and -5.

- anonymous

look at what i wrote before .
4-5=-1
4*-5=-20

- anonymous

(a-1) (a-10)

- anonymous

not -10 I meant a-1 * a-20

- anonymous

a^2-11a+10 is it ur equation ?

- anonymous

a^2-21a+20 is it ur equation

- anonymous

So confusing. :/

- anonymous

don't be confuse it's need just practice .
look at what i done

- anonymous

for second one as i wrote before the answer is :
a-5*a+4

- anonymous

ok..

- anonymous

i think the third one is not correct but let's check forth one :

- anonymous

The question for #2 is, a^2 – a – 20. So, I have to find the product of -a and the sum of -20, right?

- anonymous

All those up top are questions, I have to factor all of them.

- anonymous

u know (a+b)^2= a^2+2ab+b^2
can u guess what we should put in my equation instead b ?
because u see that first term didn't change

- anonymous

ok i solve num 3 as well but first the easier

- anonymous

Let's do #2, again.

- anonymous

a^2 – a – 20

- anonymous

ok

- anonymous

What would I do first?

- anonymous

for factories as i remember we have some ways can u tell me the ways ?

- anonymous

Find the product of one and the sum of another.

- anonymous

plz tell me all the method

- anonymous

I don't know..

- anonymous

one is (x+b)(x+a)=x^2+(a+b)+ab
that's what u mentioned .

- anonymous

fortunately we can solve #2 with this :
so look at 20
tell me product of which numbers make 20?

- anonymous

10*2

- anonymous

and 1- - 2 = 8

- anonymous

10 - 2 = 8

- anonymous

so 10 and 8?

- anonymous

look at our formula
coefficient of x is equal to sum of the numbers , am i correct ?

- anonymous

Yse.

- anonymous

ok now tell me is the sum of 10 and 2 equal to -1 ?

- anonymous

10 + 2 = 12. 12 + (-13) = -1

- anonymous

dear now what's ur number ?
check them

- anonymous

The sum of 10 and 2 is 12, right?

- anonymous

yes

- anonymous

Okay, so the sum of 10 and 2 isn't -1.

- anonymous

....

- anonymous

dear don't be confuse . may i know what's ur grade ? high school ?

- anonymous

9th.

- anonymous

where r u from ?

- anonymous

I just need to complete these 5 questions for my assignment or I get kicked out of my class. I'm from USA.

- anonymous

dear i'm here till tomorrow morning and i'll help u .
u r just 16 years old . never mind dear no one kick u out

- anonymous

lets learn it again with each other ok ?
ready ?
fasten ur seat belt

- anonymous

I'm 17. I've failed Algebra 3 times. I just don't understand it. I'd be graduated by now if it wasn't for Algebra.

- anonymous

u r a genius . may i know ur name ?

- anonymous

Possibly. What's yours?

- anonymous

dear algebra is sweet if u touch it and guess it .

- anonymous

my name is roya . i'm iranian and i'm 21 . i'm electrical engineering student and mu=y name means dream . any thing else ? i'm a girl

- anonymous

Ha. I'm a boy, 17 the name is Dylan and I'm from Florida.

- anonymous

ok are u ready ?

- anonymous

My name is Careless because eeveryone calls me that and I don't care about anything but computers and programming and processing. Yes, I'm ready. Let's start with #2... again. please.

- anonymous

dear look at # 2 . and compare it with our formula
a^2-a-20

- anonymous

our formula for this one is
x^2+(a+b)x+ab

- anonymous

ok..

- anonymous

so we should find 2 numbers which their mlt = -20 and their sum = -1
ok ?

- anonymous

mlt=multiple

- anonymous

ok.

- anonymous

so tell me the numbers which their mlt = -20

- anonymous

-10 * 2

- anonymous

can u tell me their sum ?

- anonymous

sum of...?

- anonymous

-10 + 2?

- anonymous

as u and me know their sum is 10-2 =8
ok ?

- anonymous

or as u wrote -10+2=-8

- anonymous

ok..

- anonymous

none of them are equal to -1 . am i right ?

- anonymous

Right.

- anonymous

so let's try another numbers . tell me two other number's which mlt=-20

- anonymous

-5*4

- anonymous

ok and tell me the sum

- anonymous

-5 + 4 = -1///

- anonymous

(x-5) (x+4) .... ^_^

- anonymous

so u find two numbers which mlt=-20 and sum = -1
so put them in our formula

- anonymous

such a genius boy . u should proud of urself .

- anonymous

know multiple two terms to check ur answer .

- anonymous

So, I got it right?

- anonymous

ok i give u another ex and plz solve it for me .

- anonymous

x^2+5x+6

- anonymous

ok...

- anonymous

mlt of 5 and sum of 6.. is....

- anonymous

oh oh ! mlt=6 sum=5

- anonymous

2.5 * 2 = 5 and 3* 2 = 6...

- anonymous

ohhhhhhhhhhhhhhhhhhhhhhhhhhhhhh...

- anonymous

note that u can't change the number for sum and mlt

- anonymous

3*2 = 6 and 3+2 = 5...

- anonymous

fantastic so put them in formula

- anonymous

(x+3) (x+2)

- anonymous

great job , look at this one :
x^2+11x+18

- anonymous

first tell me the mlt and sum :

- anonymous

9-2 = 18 and 9+2 = 11. (x+9) (x+2)

- anonymous

9*2*

- anonymous

9*2 = 18 and 9+2 = 11.

- anonymous

9-2 no 9*2 dear
yes u solve it .

- anonymous

I get THOSE.. why can't I get M questions...

- anonymous

Like this.. a^2 – 5a – 20..

- anonymous

sum of 5 and mlt of 20..

- anonymous

sum of -5 and -20*

- anonymous

it's a bit more difficult

- anonymous

Ugh. Sum of -5 and mlt of -20.**

- anonymous

How so? What do I have to do now?

- anonymous

HEY. I'm going to close this question and open another one. This one is getting laggy.

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