Question

Please help! I need this done ASAP but I don’t understand it!

Answer 1

Step 1:

Write the function.

`f(x)=x^3-x^2\text{ - x - 15}`

Step 2:

From f(3) = 0

One of the zeros is x = 3

Then one of the factor is x - 3.

Step 3:

Divide the function by x - 3

Step 3:

`\begin{gathered} F\text{ind the zeros of } \\ x^2\text{ + 2x + 5} \\ x\text{ = }\frac{-b\pm\sqrt[]{b^2\text{ - 4ac}}}{2a} \\ \text{a = 1, b = 2 and c = 5} \\ \text{x = }\frac{-2\pm\sqrt[]{2^2-4*1*5}}{2*1} \\ x\text{ = }\frac{-2\pm\sqrt[]{4-20}}{2} \\ x\text{ = }\frac{-2\pm\sqrt[]{-16}}{2} \\ \text{x = }\frac{-2\pm i\sqrt[]{16}}{2} \\ \text{x = }(-2\pm4i)/(2)\text{ } \\ \text{x = -1 + 2i or -1 - 2i} \end{gathered}`

Final answer

The zeros are:

3, -1 + 2i , -1 - 2i