Question

Help?

y^2 - 12y + 20

Answer 1

Are you just combining like terms?

Answer 2

I think so?

Answer 3

whats the actual question or does it just say solve?

Answer 4

just distribute -12y so that you get a product of positive 20... you can then solve for y

Answer 5

hope you got it ?

Answer 6

Well the actual question says to: factor completely. If the polynomial is not factorable, write prime

Answer 7

it is factorable...

Answer 8

Ok so then -12 would factor down to -3

Answer 9

This is how you solve it.
y^2-12y+20
Okay, you need two numbers one that has a product of 20 and one that gives you, when added, -12.
This can be either two positives, two negatives, or a combination of the two.
Now, solving it. We know that -10 and -2 give you a product of 20 and -10 and -2, added together, give -12.
So, the answer would be (y-2)(y-10)
Because y*y= y^2
y*-10= -10y
-2*y=-2y
and -2*-10=20
Combine like terms -10y and -2y you get -12y.
Which leads us back to the original problem, y^2-12y+20.
The answer (y-2)(y-10)

Answer 10

Well both of those numbers can be factored by 4

Answer 11

2+ 10 add up to 12

Answer 12

two numbers that add up to -12 and those same two numbers to have a product of 20

Answer 13

are you confused?

Answer 14

Ok i kind of got that part

Answer 15

So then would i be getting: (y-4) (y^2 + 2y + 10)

Answer 16

No that's not it

another way of looking at it
y^2 - 12y +20 = (y - a)(y-b)

can you see that?

Answer 17

(y-a)(y-b) = y^2 - (a+b)y +ab

Answer 18

so we need to find a+b =12
and ab = 20

Answer 19

what would those two numbers be?

Answer 20

2+10=12
5 x4 =20

Answer 21

@genny7

you were given the complete (correct) answer above by @Nurali (which is against the CoC)

@genny7 It looks to me that you do not fully understand the process (or purpose) of factorising an expression. Maybe you should look back at your text and classwork and try to get the basic concepts clear.

Factorising essentially produces 2 expressions that multiply together to give the SAME as your original expression.

Answer 22

btw
@alekos made the same mistake as I did

it is
-12 and 20 (NOT 12 and 20)

Answer 23

Oh now i see what @Nurali was saying...& well i have some notes but to be honest they confuse me

Answer 24

This is used when oyu have an expression with x^2 in it.

NOTE - this current question is NOT an equation - it cannot be 'solved' but it is an expression that can be re-arranged)

SO
we are looking for 2 expressions that multiply to give an expression with x^2 in it.

The only way to get x^2 is x*x

so the 2 expressions must be (x+something) * (x+somethiing else)

OK so far?

Answer 25

Yeah i think im ok so far..i think i got it know

Answer 26

Genny. You were right with the first line of your answer
10+2 = 12, a + b = 12

then we go 10 x 2 = 20, ab = 20

so a = 10 and b = 2

putting these in the equation i wrote before and we have

(y-a)(y-b) = (y-10)(y-2) = y^2 - 12y + 20

Answer 27

........or expanding (y-10)(y-2) = y^2 - (10+2)y + 10*2 = y^2 -12y +20

do you see what's happening?

Answer 28

Yes i do see whats going on

Answer 29

ok, good

Answer 30

Yeah, thanks so much for your time and help :) @alekos

Answer 31

your welcome.