Question

The value -2 is a lower bound for the zeros of the function shown below f(x)=4x^3-12x^2-x+15

Answer 1

We are given

The value -2 is a lower bound for the zeros of the function shown below f(x)=4x^3-12x^2-x+15

So, firstly, we will find value of f(x) at x=-2

we will plug x=-2 into f(x)

we get

$f(x)=4x^3-12x^2-x+15$

we will plug x=-2

$f(-2)=4(-2)^3-12(-2)^2-(-2)+15$

now, we can simplify it

$f(-2)=-32-12\cdot \:4-\left(-2\right)+15$

$f(-2)=-63$

so,

$f(-2)=-63$

we know that any zeros always lies between positive and negative value

Here , we got f(-3)=-63 ...which is negative value

so, this is lower bound

Hence , this is TRUE