Question

f(x)=2x^2+5x+3
Solve for X

Answer 1

use grouping method and then completing the square method

Answer 2

So we can write this as (for the grouping method)

\[\large 2x^2 + 2x + 3x + 3\]

we just broke up the 5x into 2x + 3x

So now, lets group

\[\large (2x^2 + 2x) + (3x + 3)\]

And now factor a 2x out of those first parenthesis, as well as a 3 out of those 2nd parenthesis

\[\large 2x(x + 1) + 3(x + 1)\]

Now notice that we have 2 of the (x + 1) parenthesis, we just carry over 1 of those, and the 2 other terms, we put in another parenthesis

\[\large (2x + 3)(x + 1)\]

Let me know if there are any questions with this method, and then we can move onto completing the square :)

Answer 3

so for the grouping method its (2x+3)(x+1)?

Answer 4

Mmhmm, does that all make sense?

Answer 5

i dont think so :p

Answer 6

lol well then I suppose I'll have to help you more :P

Answer 7

Lol what didnt quite make sense? :)

Answer 8

like i really don't understand what the grouping method looks like i never even heard of it before :/

Answer 9

Well I mean, I never liked used it...it IS useful, but when it compares to like the quadratic formula and the completing the square method, I prefer the later..much easier to follow

BUT!! I must help you ;D haha

Answer 10

So basically, we take an equation

\[\large 2x^2 + 5x + 3\]

And we find a way to break up that 'x' term...we can break up 5x into

x + 4x
2x + 3x

so we could have tried either of those...but I could tell it was the second

From those 2 possible "break ups" we need to see if we can simplify the equation we had, with this break-up in it and see if we can get 2 other the same thing *like we had (x + 1)* if we do, we have chosen the correct grouping

and we go on from there as I did above

Answer 11

Im so lost but i gotta go to work :/ but thanks for helping me get started at least hopefully i can figure out the rest when i get home :/

Answer 12

If not, you can email me later on...I can help you out there too :)

it's on my profile here :)