Question

3x^2 +8x + 5
factoring trinomials
PLEASE HELP

Answer 1

alright, let's factor :

\[(3x + 5)(x + 1) = 0\]

use the FOIL method to check your answer ^_^

Answer 2

how do you figure them out so easy

Answer 3

skill and class :)

Answer 4

exactly lol ^_^ , practice makes perfect :)

Believe me, I was so bad at these lol

Answer 5

class hasnt helped me lol

Answer 6

class won't help, it just introduces the concept, only you can help yourself :)

Answer 7

it helps when 3 and 5 make 8 right in front of you tho, but it takes practice to notice it ...

Answer 8

i use the first and last numbers, and the signs of the middle and last numbers to figure alot of it out....

Answer 9

i have the test tomarrow so we'l see

Answer 10

there are some underlying concepts to be aware of that help.... like how the equation is constructed to begine with and that way you can more easily tear it apart

Answer 11

so on this next one- 5w^2 + 13w - 6

Answer 12

you're going to do great ^_^

Answer 13

5(6) = 30... the last signis negative so the signs are different and its subtraction.... the middle number is positive so the largest factor is the positive...

Answer 14

(w+/5)(w-/5) is my setup...

Answer 15

1,30; 2,15, 3,5 15-3=13 use it

Answer 16

(w+15/5)(w-2/5) simplify and shift

Answer 17

(w+3)(5w-2)

Answer 18

ok so what the first and last multipy out to the middle needs to add up to that number

Answer 19

want me to go slower :)

Answer 20

yes please

Answer 21

the first number is used to "calibrate" the rest. does that make sense?

Answer 22

yes

Answer 23

ok... the last number is used with the first number to find a "pool" of options for our middle number... does that make sense?

Answer 24

yea

Answer 25

5(6) = 30...what are our options...all of them...

Answer 26

the factors of 30

Answer 27

yes, what are they so we can see them :)

Answer 28

start with the obvious..1,30; and move on

Answer 29

15*2 6*5 30* 1

Answer 30

thats good, lets keep those available while we "setup" our answer

Answer 31

the last number is gotten by multiplication right? so the sign of that number tells us alot of what we need to use

Answer 32

if the sign is (-) what are our options?

Answer 33

15-2 ?

Answer 34

well get to that... but for now, focus on the sign only and not the value of the number...

our set up is this:


( w ) (w ) we need some signs....

Answer 35

one of each

Answer 36

plus and minus

Answer 37

good job.... now look at the middle number and that tells you which number is bigger... does that make sense?

Answer 38

whats the middle sign? + or -?

Answer 39

-

Answer 40

that middle number is +13 right?

Answer 41

yea

Answer 42

then we want our "bigger" numbe that we use to be (+)

(w + B )(w - L ) got it?

Answer 43

now which factor do we see that will subtract to get 13?

Answer 44

15 2

Answer 45

good

(w +15 )(w -2 )

couple more loose ends to wrap up

we used that "5" from the front to begin with and so we need to divide it out in this step like this:

(w +15/5 )(w -2/5 ) makes sense?

Answer 46

yes

Answer 47

simplify those fractions and if they still look like a fraction... move the bottom in front of its x partner like this:

(w +3 )(w -2/5 ) cant reduce anymore so move the denoms if there is any:

(w +3 )(5w -2) and were done

Answer 48

thank you so much our teacher goes to fast

Answer 49

lets do another one so I can see you do it :)

Answer 50

ok....2x^2-2x-40

Answer 51

if it cant be done like this...use the quadratic formula :)

Answer 52

first step is what?

Answer 53

find the factors of 40?

Answer 54

close, first time last for a pool

Answer 55

2(40)

Answer 56

use that first now so we can divide it later... whats our pool?

Answer 57

oh ya...let me write this down

Answer 58

no writing...must do it the hard way :)

Answer 59

ok...80

Answer 60

write it down.... :)

Answer 61

i did lol

Answer 62

what are our "factors" of 80 to choose from?

Answer 63

2*40 8*10

Answer 64

80 *1

Answer 65

1,80; 2,40; 4, 10; 8, 5

Answer 66

8 and 10 lol forgot how to multiply

Answer 67

1,80; 2,40; 4,20; 8,10; 16; 5

thats better

Answer 68

lets start setup....

2x^2-2x-40

(x )(x ) we need signs...what are they?

Answer 69

ok...both -

Answer 70

both (-) meaning? that (-)(-)=(-)?

Answer 71

no

Answer 72

one of each

Answer 73

the last number sign tells us we need to multiply some signs to get it....

Answer 74

good, and the middle tells us which is begger right?

Answer 75

or bigger depending on your accent :)

Answer 76

yes

Answer 77

(x- B )(x+L ) we good so far? you writin this down?

Answer 78

yes

Answer 79

2x^2-2x-40

what numbers from our pool will give us 2?

Answer 80

10 8

Answer 81

+10 -8

Answer 82

good. lets fill them in

(x-10 )(x+8 ) now divide out the first number that "2" we used

(x-10/2)(x+8/2) now what?

Answer 83

(x-5)(x+4)

Answer 84

thats right.... but let me check our work a second....

Answer 85

one little after thought that usually doesnt come up is this..... we could have factored out a "2" to begin with.

Answer 86

as the gcf

Answer 87

yep.... so we actually need to put it back in like this:

2(x-5)(x+4) to make everything right again :)

Answer 88

now this will work back into the original :) you tried to trick me didnt you :)

Answer 89

haha ya

Answer 90

thanks..you helped alot

Answer 91

youre welcome.... hope you do good :)

Answer 92

il get on toarrow night and let you know if your here my class is at 8am

Answer 93

8am eh... is that florida time?

Answer 94

nm

Answer 95

ahh.... your 2 or 3 hours behind me then

Answer 96

ya its 11

Answer 97

:) library is closing here at my college.... so have fun :)

Answer 98

ok im off to bed thanks again