the question is
When x3+ 30x - c is divided by x-5 the remainder is 5. What is c?
i know how to divide polynomials, but i didn't understand how to work backwards in this situation. or, should i solve it a different way? thank you!
If you can do long division, divide x3 + 30x - c by x + 5.
You get a quotient of x2 - 5x + 55.
Then you will have to subtract 275 from -c to get a remainder of 5.
The only value that -c can have is 280 which means that c must equal to -280.
