We can use some polynomial "long division" to help us with this one.....
-2x^2 + [c- 4]x + [2c - 13]
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x - 2 -2x^3 + cx^2 - 5x + 2
-2x^3 + 4x^2
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(c -4)x^2 -5x
(c - 4)x^2 -2(c - 4)x
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[2c - 13]x + 2
[2c - 13]x -2[2c - 13]
-----------------------------------------------------------------------
4c - 24
-2x^2 + [c + 2]x - [ 7 + c]
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x + 1 -2x^3 + cx^2 - 5x + 2
-2x^3 - 2x^2
-----------------------------------------------------------------------
[c + 2)x^2 -5x
[c + 2]x^2 + [c + 2)x
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- [7 + c] x + 2
- [7 + c] x - [7 + c]
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9 + c
And it's obvious that the remainders will be equal when.....
4c - 24 = 9 + c subtract c from both sides and add 24 to both sides
3c = 33 ..... so .......
c = 11
