Quadratic Equations Help: 5x^2 - 30x - 200 = 0

[MastaLock]

5x^2 - 30x - 200 = 0

5x^2 - 30x = 200

5(x^2 - 30x) = 200

(1/2) (30) = 15

(15)^2 = 225

5(x^2 - 30 + 225) = 200 + 5(225)

(x - 15)(x - 15) = (1325/5)

(x - 15)^2 = 1325/5

x - 15 = Square root 265

 

[tkhunny]

Re: Quadratic Equations Help-Am I headed in the right direct

5(x^2-30x)=200

No good. That '30' should be a '6'.

 

[MastaLock]

QE

Where are you getting the 6 from????
Thank you

 

[tkhunny]

No where near "heck". It's usually called the distributive property.

5(1+2) = 5*3 = 15 -- Right?

5(1+2) = 5*1+5*2 = 5+10 = 15 -- Right again. How did the 5 and the 2 get together?

It works the other way, too.

(15+20) = 35 -- Right?

(15+20) = (5*3 + 5*4) = 5*(3+4) = 5*7 = 35 -- Right again. How did the 5 and the 4 get apart?

 

[MastaLock]

I see where you picked up the six THANKS!!!!!!!!!!!!!!!!

 

[Denis]

Masta, do yourself a favor and go here:
http://www.math.unc.edu/Faculty/mccombs ... rmula.html