Question

pleaze help me!!!

I need two numbers that can be multiplied and = -20 but when you add the two numbers they have to = -5

Answer 1

it's impossble to be like that show me the function that u stuck with

Answer 2

a^2 – 5a – 20 here is the problem

Answer 3

a+b = -5
a*b = -20
a = -20/b
-20/b+b=-5
-20+b^2 = -5b when b!=0
b^2 +5b-20 = 0
b = -(sqrt(105)+5)/2 or b = (sqrt(105)-5)/2
so a = -20(2/(sqrt(105)-5))

Answer 4

or a = -20(-2/(sqrt(105)+5))

Answer 5

????????????????

Answer 6

-20+b^2 = -5b when b!=0(where did u get that
)

Answer 7

its suppose to look like
(x+5)(x+9)

Answer 8

my homework

Answer 9

-20/b+b=-5
(-20+b^2)/b = -5
-20+b^2 = -5b as long as b!=0

Answer 10

@savannajadey what part do you not get?

Answer 11

Are you supposed to factor
a^2 – 5a – 20
This does not factor into nice numbers

or solve
a^2 – 5a – 20=0

if this is the problem, you use the "quadratic formula"

Answer 12

how u wrote it

Answer 13

I had to complete the square for the quadratic, but I did not show all that as it would have looked ugly

Answer 14

it is not -5a its +5a

Answer 15

no its not @phi

Answer 16

no its a -

Answer 17

first i used a*b = -20 to write a in terms of b. then I plugged in for a and solved the quadratic equation. the i used my information of b to solve for a. the two sets of numbers do in fact add to -5 and multiply to -20

Answer 18

a+b = -5
a*b= -20
solve for a in eq 2
a = -20/b
no plug this into equation 1
-20/b+b = -5
now find comon denom
(-20+b^2)/b= -5 multiply both sides by b
-20+b^2 = -5b so now we have
b^2-5b-20 = 0 or we could write this as -b^2+5b+20 = 0

Answer 19

are you with me so far?

Answer 20

i need two numbers thats it

Answer 21

when u multiply then it has to = -20 and when u add them they have to = -5

Answer 22

a = (sqrt(105)-5)/2
b = -40/(sqrt(105)-5)

Answer 23

a+b = -5 and a*b = -20

Answer 24

those are two such numbers...there are two more....

Answer 25

here are your choices
1,20
2,10
4,5

if you assign opposite signs (to get -20) you have
-1+20 = 19
1 -20= -19
-2+10= +8
2-10= -8
-4+5= 1
4-5=-1

there is no -5. uh oh..

Answer 26

@phi why are those the only two choices? what is wrong with my two numbers?

Answer 27

nevermind

Answer 28

There is a solution, but it involves square roots...

Answer 29

savanna take the two numbers i gave you. add them together and you get -5 multiply them together and you get -20

Answer 30

did anyone say we can use square roots?

Answer 31

there are two sets of solutions....both involve square roots

Answer 32

It would help to know exactly what the question is/was.

Answer 33

I have solved this twice, if you have any questions feel free to ask...

Answer 34

well it says two numbers. it does not say integers or natural numbers so i assume real.

Answer 35

as we only work with real numbers when at this level(for the most part)

Answer 36

i get it @savannajadey

Answer 37

lol, what did I do that we dont get?

Answer 38

@savannajadey do you understand how I got to the quadratic?

Answer 39

nope

Answer 40

a^2-5a-20=0
a^2-5a-14(-6)=0
(a-7)(a+2)-6=0

Answer 41

how is sound

Answer 42

but when u multiply then it doesnt = -20

Answer 43

yeah but first i did the simplifying

Answer 44

ok

Answer 45

-14-6=-20

Answer 46

when you multiply the two numbers I gave it does = -20

Answer 47

dn't forget best answer plz

Answer 48

what are the two number

Answer 49

it's 7 and 2

Answer 50

-7 and +2

Answer 51

-7*2 != -20

Answer 52

but thoose multiplied dont = -20

Answer 53

yeah but we add to the function (-6)

Answer 54

the two numbers are -40/(sqrt(105)-5) and (sqrt(105)-5)/2
twy it out.... there is not two such integers, and I can show a proof for that...

Answer 55

u can only hav two number @moha_10

Answer 56

moha_10 we cant make a function we already have the two relations a+b = -5 and a*b=-20 we cant change the two relations

Answer 57

okay i did it two number

Answer 58

there just simply # like 5 and -6

Answer 59

ok @savannajadey
a+b = -5
a*b= -20
solve for a in eq 2
a = -20/b
no plug this into equation 1
-20/b+b = -5
now find comon denom
(-20+b^2)/b= -5 multiply both sides by b
-20+b^2 = -5b so now we have
b^2-5b-20 = 0 or we could write this as -b^2+5b+20 = 0
tell me what part of this you dont get.

Answer 60

@zzr0ck3r all has his or her way

Answer 61

there are no such "simple" numbers.

Answer 62

what @moha_10 ?

Answer 63

@zzr0ck3r what are the two numbers u said it was

Answer 64

-40/(sqrt(105)-5) and (sqrt(105)-5)/2

Answer 65

ya @zzr0ck3r ive done this lession for the last hr now

Answer 66

alright but the number that i added to it's not realated to two numbers

Answer 67

nevermind ill figure it by myself

Answer 68

@savannajadey tell me what you dont understnad from that I just posted and we can go from there. If you check those numbers they work and I can show you how to get there. but stay with me and stop with the attempts at a natural or integer. there is no such numbers.

Answer 69

the two numbers I gave you will work and there are two more, that is all, there are no other numbers that will work.

Answer 70

yes there is im doing factoring trianomials and there are only two numbers

Answer 71

?

Answer 72

?

Answer 73

if you look at what I showed you can see that there are no such "simple" numbers...I dont understand what you are saying that because your doing trinomial factoring there must be two such numbers?

Answer 74

nmnm nm nm nm

Answer 75

ok but do you see that the two numbers I gave you do in fact add to -5 and multiply to -20?