Three ways to do it:
Method 1: Long division:
x³ + 4x² + 16x + 64
x - 4)x4 + 0x³ + 0x² + 0x - 256
x4 - 4x³
4x³ + 0x²
4x³ - 16x²
16x² + 0x
16x² - 64x
64x - 256
64x - 256
0
The solution is
x³ + 4x² + 16x + 64
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Method 2: Synthetic division:
4 | 1 0 0 0 -256
| 4 16 64 256
1 4 16 64 0
The solution is
x³ + 4x² + 16x + 64
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Method 3: Factoring and canceling:
(x+4)(x²+16)
You can leave it like that or multiply it out using FOIL:
x³ + 16x + 4x² + 64
or in descending order:
x³ + 4x² + 16x + 64, same answer as when using the long division method.
Edwin