Step by Step Solution
Step by step solution :
Step 1 :
Equation at the end of step 1 :
(3x2 • x) - 14 = 0Step 2 :
Trying to factor as a Difference of Cubes:
2.1 Factoring: 3x3-14
Theory : A difference of two perfect cubes, a3 - b3 can be factored into
(a-b) • (a2 +ab +b2)
Proof : (a-b)•(a2+ab+b2) =
a3+a2b+ab2-ba2-b2a-b3 =
a3+(a2b-ba2)+(ab2-b2a)-b3 =
a3+0+0-b3 =
a3-b3
Check : 3 is not a cube !!
Ruling : Binomial can not be factored as the difference of two perfect cubes
Polynomial Roots Calculator :
2.2 Find roots (zeroes) of : F(x) = 3x3-14
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 -14.
The factor(s) are:
of the Leading Coefficient : 1,3
of the Trailing Constant : 1 ,2 ,7 ,14
Let us test ....
| P | Q | P/Q | F(P/Q) | Divisor | |||||
|---|---|---|---|---|---|---|---|---|---|
| -1 | 1 | -1.00 | -17.00 | ||||||
| -1 | 3 | -0.33 | -14.11 | ||||||
| -2 | 1 | -2.00 | -38.00 | ||||||
| -2 | 3 | -0.67 | -14.89 | ||||||
| -7 | 1 | -7.00 | -1043.00 | ||||||
| -7 | 3 | -2.33 | -52.11 | ||||||
| -14 | 1 | -14.00 | -8246.00 | ||||||
| -14 | 3 | -4.67 | -318.89 | ||||||
| 1 | 1 | 1.00 | -11.00 | ||||||
| 1 | 3 | 0.33 | -13.89 | ||||||
| 2 | 1 | 2.00 | 10.00 | ||||||
| 2 | 3 | 0.67 | -13.11 | ||||||
| 7 | 1 | 7.00 | 1015.00 | ||||||
| 7 | 3 | 2.33 | 24.11 | ||||||
| 14 | 1 | 14.00 | 8218.00 | ||||||
| 14 | 3 | 4.67 | 290.89 |
Polynomial Roots Calculator found no rational roots
Equation at the end of step 2 :
3x3 - 14 = 0
Step 3 :
Solving a Single Variable Equation :
3.1 Solve : 3x3-14 = 0
Add 14 to both sides of the equation :
3x3 = 14
Divide both sides of the equation by 3:
x3 = 14/3 = 4.667
When two things are equal, their cube roots are equal. Taking the cube root of the two sides of the equation we get:
x = ∛ 14/3
The equation has one real solution
This solution is x = ∛ 4.667 = 1.67110
One solution was found :
x = ∛ 4.667 = 1.67110How did we do?
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