Question

i need help on how to solve factors, I'm in geometry! please help me, i have a D in this class!

Answer 1

which factor?

Answer 2

its this 4x+20x+120=0

Answer 3

\[4x^2+20x+120=0\]
or what?

Answer 4

yeah what you wrote, how do you solve it?

Answer 5

It's helpful to first simplify the expression into a form that looks something like this:\[x^2+ax+b=0,\]where \(a\) and \(b\) are numbers (if you can).

Answer 6

First, you factor out the 4 because all 3 coefficients are divisible by 4.
\[4(x^2+5x+30)=0\]
Which you can simplify to \[x^2+5x+30=0\]
Then you use the quadratic formula
\[x=\frac{-b \pm \sqrt{b^2-4ac}}{2a}\]
where a=1, b=4, and c=30

Answer 7

roots are imaginary.....

Answer 8

i think b=5....

Answer 9

wait what? whats the quadratic formula? my teacher hasn't thought us that yet.

Answer 10

@sammyiko: Time to sue your teacher.

Answer 11

The quadratic formula is a means to come up with the roots of a polynomial of the form\[ax^2+bx+c=0,\]\[\forall a, b, c \in \mathbb{R}.\]

Answer 12

http://www.math.com/students/calculators/source/quadratic.htm

Answer 13

Also, if b^2-4ac is negative, then there is no solution to the problem

Answer 14

If you are in geometry then your teacher probably wants you solve it graphically ...

Answer 15

so in this case, there is no solution because 5^2-4*1*30=25-120 which is negative

Answer 16

it's not really NO solution, just imaginary

Answer 17

Also, if b^2-4ac is negative, then there is no solution to the problem --- You mean no real solutions isn't ?

Answer 18

just imaginary

Answer 19

i feel so stupid! i have no idea what you said, okay so its x2(squared)+5x+30=0 so its (x+5)(x+6)?

Answer 20

WHAAAAT!

Answer 21

if you haven't studied imaginary numbers yet that's ok

Answer 22

No because\[(x+5)(x+6)=x^2+11x+30.\]

Answer 23

When you graph it, it doesn't cross the x-axis, so there isn't a solution because the solutions to a quadratic equation are where it crosses the x-axis.

Answer 24

so no solution to 4x2(squared)+20x+25=0?

Answer 25

It's not a zero on the real plane, but if you allow complex ones...

Answer 26

I've found this website useful when I'm lazy
http://www.wolframalpha.com/

Answer 27

and no, there isn't a solution if you're in high school geometry.

Answer 28

4x2+20x+120=0

Answer 29

yeah I'm in high school geometry

Answer 30

true, not for high school geometry. I think the numbers should stay real, especially if you don't know imaginary ones.

Answer 31

i went to that website, but i need to know how to solve this, my teacher said its like algebra 2 trig stuff.

Answer 32

trig? are you supposed to know trig?

Answer 33

Really? I learned about quadratic equations in Algebra I

Answer 34

no! but he said we're suppose to learn a little, he's crazy

Answer 35

You can just show him the graph of the function

Answer 36

is this right? x2-16x+55 is (x+5)(x-11)?

Answer 37

no...
(x+5)(x-11)=x^2-6x-55

Answer 38

sorry...x^2-16x+55 isn't factorable, I don't think

Answer 39

wait whats ^ suppose to mean?

Answer 40

to the power of
x^2 is x(squared)

Answer 41

oh okay so its not factorable

Answer 42

can you factor
x^2-x-2
???

Answer 43

BTW
x^2-16x+55=(x-5)(x-11)

Answer 44

oh okay! what about 6x^2+29x+35? i don't get how to solve the 6 thingy

Answer 45

these are ugly...
no common factors...

Answer 46

so its "not factorable"?

Answer 47

It is, it's just a tricky one
are you very comfortable with things like
x^2-x-2
???
factor if you can

Answer 48

um ye(:

Answer 49

are you sure?
it's pointless to do more difficult ones if you can't do this
what's the answer?

Answer 50

(x-2)(x+1)?

Answer 51

good!
so now I guess we'll try
6x^2+29x+35
There is a more efficient way to do this, but here's how I do itWe know there will be + signs all through because the last number is positive. what numbers should be in the blanks?
on the right of each set of parentheses they will nee do be numbers that multiply to 35, so what can they possibly be?