Friday

March 6, 2015

March 6, 2015

Posted by **Mary** on Saturday, June 27, 2009 at 10:56am.

x^2-3x-12=0

(x^2-4)=0 (x+3)=0

x^2=4 x+3+0

x=4 x=-3

Am i on the right path or just way off??

- mathematics -
**Reiny**, Saturday, June 27, 2009 at 11:15amI am assuming there is only the one equation

x^2 - 3x - 12 = 0, because what follows makes no sense

First of all your quadratic does not factor, so you will have to either use the quadratic equation formula or complete the square.

let's use the formula:

x = (3 √(9-4(1)(-12))/2

= (3 √57)/2

Use your calculator if you need a decimal equivalent.

- Mathematics -
**Mary**, Saturday, June 27, 2009 at 11:54amOk i may be dense but i dont ge tthe formula cause when i work out

3 } (9-4(1)(-12))/2

I get 60 not 57, and i dont understand how you got 9 or 4 either

- mathematics -
**Reiny**, Saturday, June 27, 2009 at 12:03pmfor any quadratic equation

ax^2 + bx + c = 0

x = (-b √(b^2 - 4ac))/(2a)

so in our case

a = 1, b = -3, and c = -12

look at the second example on this page

http://www.nipissingu.ca/calculus/tutorials/quadratics.html

**Answer this Question**

**Related Questions**

maths - Show that the equation (1) divided by (x+1) - (x)divided by (x-2)=0 has ...

Alegbra - I need help, my teacher says that I'm half way right with this but ...

gce further mathematics - The roots of the equation x^4 - 3x^2 + 5x - 2 = 0 are ...

mathematics - Use the discriminant to determine the number of real roots the ...

Algebra - The equation x^2+px+q=0, q cannot be equal to 0, has two unequal roots...

Math - 3 times the square root of 3. Would I be right in saying that just ...

mathematics - if a=5 b=108 c=190 then find the equation whose roots are double ...

Calculus - relative extrema x^4-2x^2+5 so far I know how to find the derivative ...

Math - I understand how to do these kind of problems except this one. Write the ...

Algebra - I am suppose to come up with an real life example where radical ...