# Write a polynomial equation with integer coefficients that has the given roots

To finish this we just need to determine the two numbers that need to go in the blank spots. We can narrow down the possibilities considerably. Basically, the procedure is carried out like long division of real numbers. The procedure is explained in the textbook if you're not familiar with it. One key point about division, and this works for real numbers as well as for polynomial division, needs to be pointed out.

When you divide the dividend by the divisor, you get a quotient and a remainder. To check the problem, you multiply the divisor by the quotient and add the remainder to get the dividend.

If the remainder is 0, then we say that the divisor divides evenly into the dividend. We have just factored the function f x into two factors, d x and q x. Remainder Theorem When a polynomial function f is divided by x-k, the remainder r is f k.

Okay, now in English. Now, tie that into what we just said above. If the remainder is zero, then you have successfully factored the polynomial. Plus, you now have a factored polynomial the quotient which is one less degree than the original polynomial.

If the quotient is down to a quadratic or linear factor, then you can solve and find the other solutions. Synthetic Division To divide a polynomial synthetically by x-k, perform the following steps. Setup Write k down, leave some space after it. On the same line, write the coefficients of the polynomial function.

Make sure you write the coefficients in order of decreasing power. Be sure to put a zero down if a power is missing.

## Graphing and Finding Roots of Polynomial Functions – She Loves Math

Place holders are very important For now, leave a blank line. Draw the left and bottom portions of a box. The left portion goes between the k and the coefficients. The bottom portion goes under the blank line you left. Synthetic Division Once you have things set up, you can actually start to perform the synthetic division.

Bring the first coefficient down to the bottom row below the line Multiply the number in the bottom row by the constant k, and write the product in the next column of the second row above the line. Add the numbers in the next column and write the total below the line.

Repeat steps 2 and 3 until all the columns are filled. Interpreting the Results The very last value is the remainder. If the remainder is zero, you have found a zero of the function.

The rest of the values are the coefficients of the quotient. Each term will be raised to the one less power than the original dividend. If it was a fourth degree polynomial to start with, the quotient will be a third degree polynomial. Warnings You can only use synthetic division as described above to divide by x-k.

That is, it must be a linear factor, and the leading coefficient must be a one. There are similar ways to divide by a quadratic, cubic, etc, but for some reason, they aren't taught anymore no, they won't die with me, I'm sure someone else knows them, too, but thanks for your concern.

Complex Roots Complex solutions come in pairs.

## Abstract algebra - How to find a polynomial from a given root? - Mathematics Stack Exchange

Square Roots Solutions involving square roots also come in pairs. The same is not necessarily true of other roots. Descartes' Rule of Signs This is not in your text! The maximum number of positive real roots can be found by counting the number of sign changes in f x.

The actual number of positive real roots may be the maximum, or the maximum decreased by a multiple of two. The maximum number of negative real roots can be found by counting the number of sign changes in f -x. The actual number of negative real roots may be the maximum, or the maximum decreased by a multiple of two.

Complex roots always come in pairs.You will be given a polynomial equation such as 2 7 4 27 18 0x x x x4 3 2+ − − − =, and be asked to find all roots of the equation. The Rational Zero Test states that all possible rational zeros are given . Quadratic Equation.

Quadratic equation is a second order polynomial with 3 coefficients - a, b, c. The quadratic equation is given by: ax 2 + bx + c = 0.

## Long Division of Polynomials

The solution to the quadratic equation is given by 2 numbers x 1 and x We can change the quadratic equation to the form of. Nov 21,  · A discriminant is simply a number that gives us information about the roots of a polynomial (answers) to your cubic equation are given by the formula -(b + u n C + Δ0/(u n C)) To solve a cubic equation, start by determining if your equation has a constant.

If it doesn't, use the quadratic formula to solve metin2sell.com: K. Voiceover:So we have a polynomial right over here. We have a function p(x) defined by this polynomial.

It's clearly a 7th degree polynomial, and what I want to do is think about, what are the possible number of real roots for this polynomial right over here.

If one root of a quadratic equation is an irrational root 3+4sqrt5, then the other root of the quadratic equation should be sqrt5, as the irrational roots occur in pairs for a any polynomial. The polynomial has decimal coefficients, To find the the polynomial with integer coefficients multiply by 2 to get rid of the fractions: = 2(x 3 + x 2 - x - 3) = 2x 3 + 5 x 2 - x - 6.

3 Ways to Solve a Cubic Equation - wikiHow