What is (x+9)(x^3+3x-8) 

3 Answers | Add Yours

justaguide's profile pic

justaguide | College Teacher | (Level 2) Distinguished Educator

Posted on

What has been given is not an equation but the product of two terms


=> x^4 + 9x^3 + 3x^2 + 27x - 8x - 72

If the equation to be solved is (x+9)(x^3+3x-8) = 0, equate each of the terms to 0.

x + 9 = 0

=> x = -9

x^3+3x-8 = 0 can be solved by factorization. The function provided in the link to find roots of a cubic equation has to be used. This gives the roots: `(sqrt(17)+4)^(1/3)*(-sqrt(3)*i/2-1/2)-(sqrt(3)*i/2-1/2)/(sqrt(17)+4)^(1/3)`, `(sqrt(17)+4)^(1/3)*(sqrt(3)*i/2-1/2)-(-sqrt(3)*i/2-1/2)/(sqrt(17)+4)^(1/3)` and `(sqrt(17)+4)^(1/3)-1/(sqrt(17)+4)^(1/3) `

elekzy's profile pic

elekzy | Student, Grade 11 | (Level 1) Valedictorian

Posted on

multiply each term in the first bracket by each term in the second


collect like terms



You can use Pascal's Triangle to solve this.

We’ve answered 317,688 questions. We can answer yours, too.

Ask a question