Add the following polynomials: (3x^2 - 5x - 7) and (-9x^3 + 4x^2 - 9)  

2 Answers | Add Yours

justaguide's profile pic

justaguide | College Teacher | (Level 2) Distinguished Educator

Posted on

The sum of the polynomials  (3x^2 - 5x - 7) and (-9x^3 + 4x^2 - 9) has to be determined.

3x^2 - 5x - 7 + (-9x^3) + 4x^2 - 9

take the terms with the same power of x together

=> -9x^3 + 3x^2 + 4x^2 - 5x - 7 - 9

=> -9x^3 + 7x^2 - 5x - 16

The sum of (3x^2 - 5x - 7) and (-9x^3 + 4x^2 - 9) is -9x^3 + 7x^2 - 5x - 16

dylee's profile pic

dylee | High School Teacher | (Level 1) eNoter

Posted on

In the summation of polynomial, the coefficient of the term with the same variable should be added together.

For example, x^2 with the coefficient 3 should be added to 4x^2, resulting in (4+3)x^2 = 7x^2

In this way, the calculation can be done:

(3x^2-5x-7)+(-9x^3+4x^2-9) = -9x^3+(3+4)x^2-5x-(7+9)
                                              = -9x^3+7x^2-5x-16

We’ve answered 318,912 questions. We can answer yours, too.

Ask a question