Math Question, find x (1 Viewer)

[Twickel]

find the values of x for 3x^2+2x-1=0
show working

 

[lyounamu]

find the values of x for 3x^2+2x-1=0
show working

Using quadratic formula:

x = (-2+-(plus & minus) sqrt(4 - 4 . 3 . -1))/6
= (-2 +- sqrt (16))/6
= -1 or 1/3

And please don't post up the maths question on this forum. There is a maths forum for purpose.

 

[Twickel]

How come if I use the quadratic formula x=-b+- sqrt of b^2-4ac it doesnt work.

Could someone do it using the quadratic equation, or is their a rule when not to use it.

oh I am sorry. Last time.

thankyou for clearing that up.

 

[z600]

you forgot the /2a

lyounamu already did it with the quadratic equation/formula. The quadratic formula can be applied to any qudratic equation unless it has unreal roots (you still can but you just get i)

 

[pinkslip]

umm the quadratic equation works with ALL of those types of questions, only that it is too time consuming...

for that question, u can simply work it out straight forward through factorising and then making the equation equal to zero in order to find what x is, so:

3x^2 + 2x - 1

now becomes

(3x-1) (x+1) through factorisation

and now

(3x-1) (x+1) = O inorder to find what x is

now x would then equal to 1/3 and -1

 

[milolamb]

Don't forget the cross method...
It's usually the most mark for something you can guess work ^^