Mathhhhs Helppp

Les_Rebels123

help with this pleaseee
(x+a)(x^2+bx+2)=x^3-2x^2-x-6

find values for a and b

i know the answers, just the working out that i cant do, :P

thanksss in advance

animaX

Multiply out the brackets on the LHS so that it looks just like the RHS and then you can compare co-efficients with co-efficients. You should be able to determine a and b from that.

Les_Rebels123

Have tried.... reallly really have, Ill post what i have 2 mins, ill open it up

Les_Rebels123

x^3-2x^2-x-6=x^3+bx^2+2x+ax^2+abx+2a
okay, so a=-3 got that, 2a=-6, -6/2=-3 but as for b?? if you could help

thanks

rainbow kirby

Match the coefficients...

(a + b) * x^2 = -2 * x^2

(2 + ab) * x = -x

2a = -6

Work it out from there

Les_Rebels123

thanks rainbow, that answer is just for a???
i have a, can you show me how to get b?

thanks

just on a little note,
what do you mean with the * ?

rainbow kirby

* is the symbol for multiplication. I have a habit of typing maths on forums as if I'm using Matlab! :pac:

You have a choice of two equations in both a and b there, use the simpler one with the answer you've already got for a to get b.

Les_Rebels123

would i be right in saying, that you say/figured that

a= -3
b= 2

Gael23

Now you substitute 3 for a, so everywhere theres an a you put 3. Then just add it up.

rainbow kirby

I didn't get 2 for b when I worked it out.

Take a + b = -2 and put the value of -3 for a into it.

Les_Rebels123

guys, i know i seem very stupid in not getting these answers, but, when your teacher explains it one way, and someone else explains it another, it just makes it worse,
thanks guys for your help.

haha, did 2 of em, got right answers, and the other 1, well at this stage, fed up, maths are gone for 2nite, I have accounting,business,french,chemistry,Construction,Irish, AND History homework to do, all due in 2moro.... this is gonna be a reaall looong nite,

thanks again for the help