Answer:
c = 8
Explanation:
4x³ + cx² + x + 2 ÷ x + 2 = ...
first we divide
4x³ + cx² by x + 2
and that is by doing 4x³/x = 4x².
4x³ + cx² + x + 2 ÷ x + 2 = 4x² ...
now we need to find the remainder, as with regular number divisions :
4x² × (x + 2) = 4x³ + 8x²
which we need to subtract from the left side
4x³ + cx² + x + 2 ÷ x + 2 = 4x² ...
- 4x³ + 8x²
----------------
0 cx² - 8x²
now we pull down the next position (x) and divide that by x + 2
4x³ + cx² + x + 2 ÷ x + 2 = 4x² + 1
- 4x³ + 8x²
----------------
0 cx² - 8x² + x
and the same again, to find the remainder, we have to subtract 1×(x + 2) = x + 2 from the left side
4x³ + cx² + x + 2 ÷ x + 2 = 4x² ...
- 4x³ + 8x²
----------------
0 cx² - 8x² + x
- x + 2
-----------------------------
cx² - 8x² 0 0
the polynomial is divisible by x + 2, if the remainder is 0.
so,
cx² - 8x² = 0
cx² = 8x²
c = 8