+0

x^2-2x-24=0

0
781
3

x^2-2x-24=0

Apr 26, 2014

#3
+109520
+5

Hi Bioschip,

I really like your logic there.  And of course you are correct.  6 IS ONE of the answers !

When you have an equation like this with an x2 term, there are usually 2 answers.

this is how it is done.

\$\$x^2-2x-24=0\$\$

First I need to factorise this.  Factors are things that multiply to get the answers

I need 2 numbers that multiply to -24  (one will need to be neg and one pos)

they also need to add to -2   (How about -6 and 4, they work)

so the question becomes

\$\$(x-6)(x+4)=0\$\$      that is what Bertie got up to!

NOW, if two things multiply together to give 0 then one of them (or both of them) must equal 0.

so either \$\$x-6=0\$\$  or  \$\$x+4=0\$\$

so   \$\$x=6\$\$   OR    \$\$x=-4\$\$

Maybe you would like to try this one   \$\$x^2+5x+4=0\$\$   ???

----------------------------------------------------------

NOW I want people to start learning to use LaTex which is how we display the maths stuff.

So here is a little lesson.

Press the LaTex button, type (x-6)(x+4)=0  then press ok.

See how it displays.

If you want to know how to display anything else, please ask.  Remember, Members get priority answering.

-----------------------------------------------------------------

Apr 26, 2014

#1
+158
+5

if you are looking for the value of x then that is six because if you use Pedmas then 6^2 comes first and that is equal to 36 then your problem is equal to 36-2x-24=0 then you use 2*6 get 12 and your problem is equal to 36-12-24=0 so you probably no what to do on from there 36-12=24 and 24-24=0.

Apr 26, 2014
#2
+890
+5

(x - 6)(x + 4) = 0.

Apr 26, 2014
#3
+109520
+5

Hi Bioschip,

I really like your logic there.  And of course you are correct.  6 IS ONE of the answers !

When you have an equation like this with an x2 term, there are usually 2 answers.

this is how it is done.

\$\$x^2-2x-24=0\$\$

First I need to factorise this.  Factors are things that multiply to get the answers

I need 2 numbers that multiply to -24  (one will need to be neg and one pos)

they also need to add to -2   (How about -6 and 4, they work)

so the question becomes

\$\$(x-6)(x+4)=0\$\$      that is what Bertie got up to!

NOW, if two things multiply together to give 0 then one of them (or both of them) must equal 0.

so either \$\$x-6=0\$\$  or  \$\$x+4=0\$\$

so   \$\$x=6\$\$   OR    \$\$x=-4\$\$

Maybe you would like to try this one   \$\$x^2+5x+4=0\$\$   ???

----------------------------------------------------------

NOW I want people to start learning to use LaTex which is how we display the maths stuff.

So here is a little lesson.

Press the LaTex button, type (x-6)(x+4)=0  then press ok.

See how it displays.

If you want to know how to display anything else, please ask.  Remember, Members get priority answering.

-----------------------------------------------------------------

Melody Apr 26, 2014