4x^2 – 8 = 0

trying to factor it and having trouble coming up with a 0 in x

January 25th, 2011 @9:51 am

4x^2 – 8 = 0

x^2 = 2

x = +/- sqrt(2)

January 25th, 2011 @10:10 am

why are you using quadratic formula? just use, dare i say it – your brain.

January 25th, 2011 @10:50 am

4x^2=8

x^2=2

x= plus or minus square root of 2

January 25th, 2011 @11:33 am

(0 +- sqroot(0 – (4)(4)(-8))) / (4)(2)

+- 8sqroot(2)/8

the answer is sqroot of 2

January 25th, 2011 @12:01 pm

4x^2-8=0

4(x^2-2)=0

Divide both sides by 4

x^2-2=0

x^2=2

x= +/- sq.rt.(2)

If you were to use the quadratic formula,

4x^2-8=0 should be re-written as

4x^2+0x-8=0

a=4, b=0, c= -8

x= {-b+/-rt(b^2-4ac)} / 2a

x= {0+/-rt(0-4(4)(-8)} / 8

x={+/-rt(128)} / 8

x= +/-{rt(64)rt(2)} / 8

x= +/-8rt(2)/8

x= +rt(2) or -rt(2)

use the quadradtic equation. -b +- sqrt( b^2 -4ac) / 2a

4 = a

0 = b

-8 = c