Finding all zeros

[TheNascar92]

I have a polynomial for which I need to find all the zeros. I just want to know if my work is correct:

F(x)= -2x^3-15x^2+14x+48

I found one zero (2) by using the rational zeros theorem and synthetic division. After that I had the remaining quotient as my polynomial:

-2x^2-19x-24

From here i used the quadratic formula and my zeros were: 19+ i (square root of 13/2). and 19-i (square root of 13/2). Im sorry i know its really confusing to read but the "i" is the imaginary number multiplying the radical. If anyone could just tell me whether or not my work is correct thank you

 

[Denis]

-2x^2-19x-24
From here i used the quadratic formula and my zeros were: 19+ i (square root of 13/2). and 19-i (square root of 13/2).

Try again CAREFULLY : you should not end up with anything imaginary.

 

[mmm4444bot]

… I found one zero (2) … I had the remaining quotient …

-2x^2 - 19x - 24 ? Your work is correct, up to this point.

… If anyone could just tell me whether or not my work is correct …

The roots of the quadratic polynomial are two Rational numbers, one of which is an Integer.

 

[Deleted member 4993]

And both the roots are negative.

 

[wjm11]

I have a polynomial for which I need to find all the zeros. I just want to know if my work is correct:

F(x)= -2x^3-15x^2+14x+48

Here's one way to check your work. If you have a graphing calculator, input your eqn

y = -2x^3-15x^2+14x+48

and graph it. Count how many times the graph crosses the x-axis. This is the number of Real zeros/roots. You can also determine what the values of the roots are.

Hope that helps.

 

[TheNascar92]

Thank you everyone