Step by Step Solution
Step by step solution :
Step 1 :
Equation at the end of step 1 :
(22x2 • x) - 5 = 0Step 2 :
Trying to factor as a Difference of Cubes:
2.1 Factoring: 4x3-5
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 : 4 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) = 4x3-5
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 4 and the Trailing Constant is -5.
The factor(s) are:
of the Leading Coefficient : 1,2 ,4
of the Trailing Constant : 1 ,5
Let us test ....
| P | Q | P/Q | F(P/Q) | Divisor | |||||
|---|---|---|---|---|---|---|---|---|---|
| -1 | 1 | -1.00 | -9.00 | ||||||
| -1 | 2 | -0.50 | -5.50 | ||||||
| -1 | 4 | -0.25 | -5.06 | ||||||
| -5 | 1 | -5.00 | -505.00 | ||||||
| -5 | 2 | -2.50 | -67.50 | ||||||
| -5 | 4 | -1.25 | -12.81 | ||||||
| 1 | 1 | 1.00 | -1.00 | ||||||
| 1 | 2 | 0.50 | -4.50 | ||||||
| 1 | 4 | 0.25 | -4.94 | ||||||
| 5 | 1 | 5.00 | 495.00 | ||||||
| 5 | 2 | 2.50 | 57.50 | ||||||
| 5 | 4 | 1.25 | 2.81 |
Polynomial Roots Calculator found no rational roots
Equation at the end of step 2 :
4x3 - 5 = 0
Step 3 :
Solving a Single Variable Equation :
3.1 Solve : 4x3-5 = 0
Add 5 to both sides of the equation :
4x3 = 5
Divide both sides of the equation by 4:
x3 = 5/4 = 1.250
When two things are equal, their cube roots are equal. Taking the cube root of the two sides of the equation we get:
x = ∛ 5/4
The equation has one real solution
This solution is x = ∛ 1.250 = 1.07722
One solution was found :
x = ∛ 1.250 = 1.07722How did we do?
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