Question

3x^3-4x^2-7x=0

Answer 1

Factor out x on the left side.

Answer 2

ok so i get x(3x^2-4x-7)...then what would i do

Answer 3

Ok so you know one of the roots is x = 0 right. Now the only task is to factor the quadratic equation in the parenthesis. You can do this with the quadratic formula. Are you familiar?

Answer 4

no

Answer 5

Quadratic formula is used to solve problems of the form ax^2+bx+c = 0, the answer being x = (-b+/- sqrt(b^2-4ac)/(2a). I'm surprised you haven't been taught this if you're expected to solve the above problem.

Answer 6

http://mathworld.wolfram.com/QuadraticFormula.html

Answer 7

ok so what should it look like when i plug in the numbers?

Answer 8

Your formula is 3x^2-4x-7 and the general quadratic equation is ax^2+bx+c. So in this case a = 3 b = -4 and c = -7. Just plug those numbers into the quadratic formula to acquire the other 2 roots.

Answer 9

ok so would it be (3x -2)(x +2) the roots being -2&2

Answer 10

no thats not right b/c one of them is zero

Answer 11

If you FOIL out your expression, you get 3x^3+4x-4 so that's not quite right.

Answer 12

3x^2 I mean. Yes 0 is one but there are 2 more

Answer 13

ok i'm confused what would my roots be then

Answer 14

Overall the expression can be factored out to (x)(3x+2)(x-2) = 0. The roots are the values of x which make the expression true. In this case x = 0, x =-2/3 and x = 2 would do the trick.

Answer 15

yess i got thanks that helped a lot!

Answer 16

No problem