• Jan 28th 2010, 07:15 AM
JM92
Hi
Stuck of a few Quadratic equations, just thought i may be able to get some help off here?
Heres the questions:

1) X^2 + 9X + 20 = 0

2) X^2 +5X -36 = 0

If anyone can help it will be much appreciated, also if you can show working it will be even better as i might be able to get to grips with it.

thanks
• Jan 28th 2010, 07:39 AM
masters
Quote:

Originally Posted by JM92
Hi
Stuck of a few Quadratic equations, just thought i may be able to get some help off here?
Heres the questions:

1) $X^2 + 9X + 20 = 0$

(2) $X^2 +5X -36 = 0$

If anyone can help it will be much appreciated, also if you can show working it will be even better as i might be able to get to grips with it.

thanks

Hi Jm92,

$x^2+9x+20=0$

Do you remember how to factor a quadratic polynomial?

$(x+5)(x+4)=0$

Now, set each factor = 0 and solve.

Do the other one in a similar fashion.
• Jan 28th 2010, 12:27 PM
JM92
HI
Thanks for the help masters, So is question 2 something along the lines of..
(x-9)(x-4)=0 ?
• Jan 28th 2010, 12:32 PM
masters
Quote:

Originally Posted by JM92
HI
Thanks for the help masters, So is question 2 something along the lines of..
(x-9)(x-4)=0 ?

Close, but no cigar.

$x^2+5x-36=0$

To factor the trinomial, you must come up with two numeric factors that multiply to -36 and at the same time add to +5.

The only two that meet that criteria are +9 and -4.

$(x+9)(x-4)=0$
• Jan 28th 2010, 12:34 PM
JM92
Ahh now i get it. Thanks alot for the help masters (Clapping)