Solution - Finding the roots of polynomials
Other Ways to Solve
Finding the roots of polynomialsStep by Step Solution
Step 1 :
Equation at the end of step 1 :
(32x4 - x2) + 2x
Step 2 :
Step 3 :
Pulling out like terms :
3.1 Pull out like factors :
9x4 - x2 + 2x = x • (9x3 - x + 2)
Polynomial Roots Calculator :
3.2 Find roots (zeroes) of : F(x) = 9x3 - x + 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 9 and the Trailing Constant is 2.
The factor(s) are:
of the Leading Coefficient : 1,3 ,9
of the Trailing Constant : 1 ,2
Let us test ....
P | Q | P/Q | F(P/Q) | Divisor | |||||
---|---|---|---|---|---|---|---|---|---|
-1 | 1 | -1.00 | -6.00 | ||||||
-1 | 3 | -0.33 | 2.00 | ||||||
-1 | 9 | -0.11 | 2.10 | ||||||
-2 | 1 | -2.00 | -68.00 | ||||||
-2 | 3 | -0.67 | 0.00 | 3x + 2 | |||||
-2 | 9 | -0.22 | 2.12 | ||||||
1 | 1 | 1.00 | 10.00 | ||||||
1 | 3 | 0.33 | 2.00 | ||||||
1 | 9 | 0.11 | 1.90 | ||||||
2 | 1 | 2.00 | 72.00 | ||||||
2 | 3 | 0.67 | 4.00 | ||||||
2 | 9 | 0.22 | 1.88 |
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
9x3 - x + 2
can be divided with 3x + 2
Polynomial Long Division :
3.3 Polynomial Long Division
Dividing : 9x3 - x + 2
("Dividend")
By : 3x + 2 ("Divisor")
dividend | 9x3 | - | x | + | 2 | ||||
- divisor | * 3x2 | 9x3 | + | 6x2 | |||||
remainder | - | 6x2 | - | x | + | 2 | |||
- divisor | * -2x1 | - | 6x2 | - | 4x | ||||
remainder | 3x | + | 2 | ||||||
- divisor | * x0 | 3x | + | 2 | |||||
remainder | 0 |
Quotient : 3x2-2x+1 Remainder: 0
Trying to factor by splitting the middle term
3.4 Factoring 3x2-2x+1
The first term is, 3x2 its coefficient is 3 .
The middle term is, -2x its coefficient is -2 .
The last term, "the constant", is +1
Step-1 : Multiply the coefficient of the first term by the constant 3 • 1 = 3
Step-2 : Find two factors of 3 whose sum equals the coefficient of the middle term, which is -2 .
-3 | + | -1 | = | -4 | ||
-1 | + | -3 | = | -4 | ||
1 | + | 3 | = | 4 | ||
3 | + | 1 | = | 4 |
Observation : No two such factors can be found !!
Conclusion : Trinomial can not be factored
Final result :
x • (3x2 - 2x + 1) • (3x + 2)
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