Step 1 :
To factor $ x^{3}+64 $ we can use sum of cubes formula:
$$ I^3 - II^3 = (I + II)(I^2 - I \cdot II + II^2) $$After putting $ I = x $ and $ II = 4 $ , we have:
$$ x^{3}+64 = ( x+4 ) ( x^{2}-4x+16 ) $$Step 2 :
Step 2: Identify constants $ \color{blue}{ b }$ and $\color{red}{ c }$. ( $ \color{blue}{ b }$ is a number in front of the $ x $ term and $ \color{red}{ c } $ is a constant). In our case:
$$ \color{blue}{ b = -4 } ~ \text{ and } ~ \color{red}{ c = 16 }$$Now we must discover two numbers that sum up to $ \color{blue}{ -4 } $ and multiply to $ \color{red}{ 16 } $.
Step 3: Find out pairs of numbers with a product of $\color{red}{ c = 16 }$.
PRODUCT = 16 | |
1 16 | -1 -16 |
2 8 | -2 -8 |
4 4 | -4 -4 |
Step 4: Because none of these pairs will give us a sum of $ \color{blue}{ -4 }$, we conclude the polynomial cannot be factored.