Test next week having a problem

jacklc2014

don't know if it's me or the book can only get this half done

8x*2 - 34x -9/ 4x+1. Multiply by 3x / 4x*2-81


*2 = Squared

Anyone help me please.

TheBody

jacklc2014 wrote: »

don't know if it's me or the book can only get this half done

8x*2 - 34x -9/ 4x+1. Multiply by 3x / 4x*2-81


*2 = Squared

Anyone help me please.

Hi there. So I hope I'm reading it correctly by saying you want to find:

[Latex]\frac{8x^2-34x-9}{4x+1}\times\frac{3x}{4x^2-81}[/Latex]

The rules of fractions apply to this in the same way as they would apply to regular fractions. So just multiple top by the top and the bottom by the bottom.

sligo camper

break it down for us Body.....

TheBody

sligo camper wrote: »

break it down for us Body.....

Forum charter says I can't just do the problem for the op. Feel free to put up attemps and I'll have a look at it for ya.

jacklc2014

(4x+2)/(4x+1) multiplied by 3x/(2x+9) that's as far as iv got.

Yakuza

I think you're on the right path, but you may have taken a slightly wrong turn with your factorisations
Starting with
[LATEX]\frac{8x^2-34x-9}{4x+1}\times\frac{3x}{4x^2-81}[/LATEX], can you factorise [LATEX]{8x^2-34x-9}[/LATEX] into [LATEX]{4x+1}[/LATEX] times something? (It will be of the form [LATEX]{ax-b}[/LATEX])

Secondly, look at [LATEX]{4x^2-81}[/LATEX]. Factorise this out -it's the difference of two squares, so it should factorise fairly easily: [LATEX]{a^2-b^2} = {(a + b)}\times(a-b)}[/LATEX].

Now look at what you have and replacing the quadratic equations (those with powers of x²) with their factors in the original problem, most of them should cancel out. The answer I got was similar to (but simpler than) the one you got.

jacklc2014

Thanks I factorised it out like you said but still can't get any more done,leaving it now,thanks for your help.

Delphi91

Try factorising the [latex]8x^2-34x-9[/latex] term again. The idea would be to get one of the factors to "cancel" with one of the terms below the line. So as Yakuza said, one of the factors might be [latex]4x+1[/latex] or it could also be one of the factors got by simplifying [latex]4x^2-81[/latex] (HINT )

jacklc2014

Got joint highest in class,thanks for help,will work on this equation over the weekend.