Mathematics 2015 JAMB Past Questions - Question 19: Divide the expression x3+7x2-x-7 by x2-1

Correct Answer

D

Explanation

x2-1√x3+7x2-x-7x3-x (7x2-7)(7x2-7)-7=x+7To divide the expression x^3 + 7x^2 - x - 7 by x^2 - 1, we can use polynomial long division.First, we divide x^3 by x^2, which gives x. We then multiply x by x^2 - 1 to get x^3 - x, and subtract this from x^3 + 7x^2 - x - 7 to get 8x^2 - x - 7.Next, we divide 8x^2 by x^2, which gives 8. We then multiply 8 by x^2 - 1 to get 8x^2 - 8, and subtract this from 8x^2 - x - 7 to get 7x - 7.Finally, we divide 7x by x, which gives 7. We then multiply 7 by x^2 - 1 to get 7x - 7, and subtract this from 7x - 7 to get 0.So, the result of the division is x + 8 with a remainder of 0. Therefore, the expression x^3 + 7x^2 - x - 7 divided by x^2 - 1 is x + 8.