Solution - Finding the roots of polynomials
Other Ways to Solve
Finding the roots of polynomialsStep by Step Solution
Step 1 :
2
Simplify ——
x2
Equation at the end of step 1 :
2 ((((3•(x2))-5x)+——)-3x)+2 x2Step 2 :
Equation at the end of step 2 :
2
(((3x2 - 5x) + ——) - 3x) + 2
x2
Step 3 :
Rewriting the whole as an Equivalent Fraction :
3.1 Adding a fraction to a whole
Rewrite the whole as a fraction using x2 as the denominator :
3x2 - 5x (3x2 - 5x) • x2
3x2 - 5x = ———————— = ———————————————
1 x2
Equivalent fraction : The fraction thus generated looks different but has the same value as the whole
Common denominator : The equivalent fraction and the other fraction involved in the calculation share the same denominator
Step 4 :
Pulling out like terms :
4.1 Pull out like factors :
3x2 - 5x = x • (3x - 5)
Adding fractions that have a common denominator :
4.2 Adding up the two equivalent fractions
Add the two equivalent fractions which now have a common denominator
Combine the numerators together, put the sum or difference over the common denominator then reduce to lowest terms if possible:
x • (3x-5) • x2 + 2 3x4 - 5x3 + 2
——————————————————— = —————————————
x2 x2
Equation at the end of step 4 :
(3x4 - 5x3 + 2)
(——————————————— - 3x) + 2
x2
Step 5 :
Rewriting the whole as an Equivalent Fraction :
5.1 Subtracting a whole from a fraction
Rewrite the whole as a fraction using x2 as the denominator :
3x 3x • x2
3x = —— = ———————
1 x2
Polynomial Roots Calculator :
5.2 Find roots (zeroes) of : F(x) = 3x4 - 5x3 + 2
Polynomial Roots Calculator is a set of methods aimed at finding values of x for which F(x)=0
Rational Roots Test is one of the above mentioned tools. It would only find Rational Roots that is numbers x which can be expressed as the quotient of two integers
The Rational Root Theorem states that if a polynomial zeroes for a rational number P/Q then P is a factor of the Trailing Constant and Q is a factor of the Leading Coefficient
In this case, the Leading Coefficient is 3 and the Trailing Constant is 2.
The factor(s) are:
of the Leading Coefficient : 1,3
of the Trailing Constant : 1 ,2
Let us test ....
P | Q | P/Q | F(P/Q) | Divisor | |||||
---|---|---|---|---|---|---|---|---|---|
-1 | 1 | -1.00 | 10.00 | ||||||
-1 | 3 | -0.33 | 2.22 | ||||||
-2 | 1 | -2.00 | 90.00 | ||||||
-2 | 3 | -0.67 | 4.07 | ||||||
1 | 1 | 1.00 | 0.00 | x - 1 | |||||
1 | 3 | 0.33 | 1.85 | ||||||
2 | 1 | 2.00 | 10.00 | ||||||
2 | 3 | 0.67 | 1.11 |
The Factor Theorem states that if P/Q is root of a polynomial then this polynomial can be divided by q*x-p Note that q and p originate from P/Q reduced to its lowest terms
In our case this means that
3x4 - 5x3 + 2
can be divided with x - 1
Polynomial Long Division :
5.3 Polynomial Long Division
Dividing : 3x4 - 5x3 + 2
("Dividend")
By : x - 1 ("Divisor")
dividend | 3x4 | - | 5x3 | + | 2 | ||||||
- divisor | * 3x3 | 3x4 | - | 3x3 | |||||||
remainder | - | 2x3 | + | 2 | |||||||
- divisor | * -2x2 | - | 2x3 | + | 2x2 | ||||||
remainder | - | 2x2 | + | 2 | |||||||
- divisor | * -2x1 | - | 2x2 | + | 2x | ||||||
remainder | - | 2x | + | 2 | |||||||
- divisor | * -2x0 | - | 2x | + | 2 | ||||||
remainder | 0 |
Quotient : 3x3-2x2-2x-2 Remainder: 0
Polynomial Roots Calculator :
5.4 Find roots (zeroes) of : F(x) = 3x3-2x2-2x-2
See theory in step 5.2
In this case, the Leading Coefficient is 3 and the Trailing Constant is -2.
The factor(s) are:
of the Leading Coefficient : 1,3
of the Trailing Constant : 1 ,2
Let us test ....
P | Q | P/Q | F(P/Q) | Divisor | |||||
---|---|---|---|---|---|---|---|---|---|
-1 | 1 | -1.00 | -5.00 | ||||||
-1 | 3 | -0.33 | -1.67 | ||||||
-2 | 1 | -2.00 | -30.00 | ||||||
-2 | 3 | -0.67 | -2.44 | ||||||
1 | 1 | 1.00 | -3.00 | ||||||
1 | 3 | 0.33 | -2.78 | ||||||
2 | 1 | 2.00 | 10.00 | ||||||
2 | 3 | 0.67 | -3.33 |
Polynomial Roots Calculator found no rational roots
Adding fractions that have a common denominator :
5.5 Adding up the two equivalent fractions
(3x3-2x2-2x-2) • (x-1) - (3x • x2) 3x4 - 8x3 + 2
—————————————————————————————————— = —————————————
x2 x2
Equation at the end of step 5 :
(3x4 - 8x3 + 2)
——————————————— + 2
x2
Step 6 :
Rewriting the whole as an Equivalent Fraction :
6.1 Adding a whole to a fraction
Rewrite the whole as a fraction using x2 as the denominator :
2 2 • x2
2 = — = ——————
1 x2
Polynomial Roots Calculator :
6.2 Find roots (zeroes) of : F(x) = 3x4 - 8x3 + 2
See theory in step 5.2
In this case, the Leading Coefficient is 3 and the Trailing Constant is 2.
The factor(s) are:
of the Leading Coefficient : 1,3
of the Trailing Constant : 1 ,2
Let us test ....
P | Q | P/Q | F(P/Q) | Divisor | |||||
---|---|---|---|---|---|---|---|---|---|
-1 | 1 | -1.00 | 13.00 | ||||||
-1 | 3 | -0.33 | 2.33 | ||||||
-2 | 1 | -2.00 | 114.00 | ||||||
-2 | 3 | -0.67 | 4.96 | ||||||
1 | 1 | 1.00 | -3.00 | ||||||
1 | 3 | 0.33 | 1.74 | ||||||
2 | 1 | 2.00 | -14.00 | ||||||
2 | 3 | 0.67 | 0.22 |
Polynomial Roots Calculator found no rational roots
Adding fractions that have a common denominator :
6.3 Adding up the two equivalent fractions
(3x4-8x3+2) + 2 • x2 3x4 - 8x3 + 2x2 + 2
———————————————————— = ———————————————————
x2 x2
Checking for a perfect cube :
6.4 3x4 - 8x3 + 2x2 + 2 is not a perfect cube
Trying to factor by pulling out :
6.5 Factoring: 3x4 - 8x3 + 2x2 + 2
Thoughtfully split the expression at hand into groups, each group having two terms :
Group 1: 2x2 + 2
Group 2: -8x3 + 3x4
Pull out from each group separately :
Group 1: (x2 + 1) • (2)
Group 2: (3x - 8) • (x3)
Bad news !! Factoring by pulling out fails :
The groups have no common factor and can not be added up to form a multiplication.
Polynomial Roots Calculator :
6.6 Find roots (zeroes) of : F(x) = 3x4 - 8x3 + 2x2 + 2
See theory in step 5.2
In this case, the Leading Coefficient is 3 and the Trailing Constant is 2.
The factor(s) are:
of the Leading Coefficient : 1,3
of the Trailing Constant : 1 ,2
Let us test ....
P | Q | P/Q | F(P/Q) | Divisor | |||||
---|---|---|---|---|---|---|---|---|---|
-1 | 1 | -1.00 | 15.00 | ||||||
-1 | 3 | -0.33 | 2.56 | ||||||
-2 | 1 | -2.00 | 122.00 | ||||||
-2 | 3 | -0.67 | 5.85 | ||||||
1 | 1 | 1.00 | -1.00 | ||||||
1 | 3 | 0.33 | 1.96 | ||||||
2 | 1 | 2.00 | -6.00 | ||||||
2 | 3 | 0.67 | 1.11 |
Polynomial Roots Calculator found no rational roots
Final result :
3x4 - 8x3 + 2x2 + 2
———————————————————
x2
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