5x^3-15z^2-20z=0 What is a complete solution set?

Question

x^4+2x^3-9x^2? is this correct

Thanks!!

Answer 1

No, that's an expression, not a solution set. I assume the z's in your question should actually be x's...

5x^3-15x^2-20x=0
<=> 5x (x^2 - 3x - 4) = 0
<=> 5x (x-4) (x+1) = 0
<=> x = 0 or x-4 = 0 or x+1 = 0
<=> x = 0, 4, -1.
So the solution set is {0, 4, -1}.

Answer 2

5z^3 -15z^2 -20z=0
5z(z^2 -3z-4)=0
5z(z-4)(z+1)=0

For 5z(z-4)(z+1) to equal zero, at least one of those three terms must be zero
If 5x=0, z=0
If z-4=0, z=4
If z+1=0, z=-1

I've taken the liberty of changing 5x^3 in your question. If it truly is 5x^3, then there is no solution, because you would have two unknowns, x and z, and only one equation.For every unknown, you must have an equation, unless you are expressing one unknown in terms of the other.

I delight in dealing with someone who has a sense of humor. That solution of x^4 +2x^3-9x^2 is a riot!
May the world laugh with both of us!

Answer 3

The solution set tells you what x equals. Solve for x.

I cannot understand what you have typed... You need to either try again or figure it out on your own.