Use factors to simplify each of the following expressions:

runswithascript

Of the 6 questions of this type for homework I've managed to complete 4 correctly but try as I might I'm having no such luck with the following.

Text & Tests 4

Page 23

Use factors to simplify each of the following expressions:

6a + 3
2a^2 + 5a +2

I've been thought when the terms in an expression have something in common 'common factors come first' so I change 6a + 3 into 3(2a +1).

Also when nothing is in common to each term like to the denominator to use the following method:

First taking the factors of the first and last terms in the and putting them on each end of a cross and then drawing 'goal posts' beneath this containing each term in the expression which I can't represent here:

2a +1
X
a +2


2a +1a 2

+5a
Above I'm told I need to guess the signs to put before the 1 and the 2 to make up +5a when added together. To get +5a when cross multiplied both signs have to be either positive or negative right? Leaving me with +1 and +2 respectively.

Now to factorise the initial expression representing the denominator I multiply from left to right on my cross:

6a + 3
2a^2 + 5a +2

3(2a+1)
(a+2)(2a+1)But the book lists the answer as:

3
2a+1

What am I doing wrong?

Would dividing the entire fraction by (2a+1) correctly leave me with:

3
a+2
If so it's closer but still not the correct answer?

Would greatly appreciate any help, it's annoying me I can't do it!!

henbane

I think you may have happened across an error in the book as [latex]\frac{3}{a+2}[/latex] looks to be the answer

Although I may have made a mistake somewhere along the way

runswithascript

henbane wrote: »

I think you may have happened across an error in the book as [latex]\frac{3}{a+2}[/latex] looks to be the answer

Although I may have made a mistake somewhere along the way

Thanks. I think you're correct as two people on irc.freenode.org's #math channel have said the same thing without anyone else correcting them

How is it you type the fractions like that?

runswithascript

henbane wrote: »

I think you may have happened across an error in the book as [latex]\frac{3}{a+2}[/latex] looks to be the answer

Although I may have made a mistake somewhere along the way

Just saw in your quoted text of my reply I need to type [*latex]\frac {first expression}{second expression}[*/latex]

[latex]\frac{1}{2}[/latex]

Unless there's an easier way through the GUI?

henbane

I don't think there's a shortcut for latex input. There's a latex sticky at the top of the forum for more info on displaying equations